diff --git a/stint/intops.nim b/stint/intops.nim
index 90ed0d2..293c3b4 100644
--- a/stint/intops.nim
+++ b/stint/intops.nim
@@ -7,155 +7,204 @@
 #
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ./private/[datatypes]
+import
+  ./private/datatypes,
+  ./private/uint_bitwise,
+  ./private/uint_shift,
+  ./private/uint_addsub,
+  ./uintops
 
 export StInt
-#export IntImpl, intImpl, UintImpl, uintImpl, bitsof # TODO: remove the need to export those
 
-#import ./private/initialization
+const
+  signMask = 1.Word shl WordBitWidth
+  clearSignMask = not signMask
 
-func zero*[bits: static[int]](T: typedesc[StInt[bits]]): T {.inline.} =
+# Signedness
+# --------------------------------------------------------
+{.push raises: [], inline, noinit, gcsafe.}
+
+func sign*(a: StInt): int =
+  if a.imp.isZero: return 0
+  if a.limbs[^1] < signMask: 1
+  else: -1
+
+func isNegative*(a: StInt): bool =
+  a.sign < 0
+
+func clearSign(a: var StInt) =
+  a.limbs[^1] = a.limbs[^1] and clearSignMask
+
+func setSign(a: var StInt) =
+  a.limbs[^1] = a.limbs[^1] or signMask
+
+func negate*(a: var StInt) =
+  a.imp.bitnot(a.imp)
+  a.imp.inc
+
+func neg*(a: StInt): StInt =
+  result.imp.bitnot(a.imp)
+  result.imp.inc
+
+func abs*(a: StInt): StInt =
+  if a.isNegative:
+    a.neg
+  else:
+    a
+
+func `-`*(a: StInt): StInt =
+  a.neg
+
+{.pop.}
+
+# Initialization
+# --------------------------------------------------------
+{.push raises: [], inline, noinit, gcsafe.}
+
+func setZero*(a: var StInt) =
+  ## Set ``a`` to 0
+  a.imp.setZero
+
+func setOne*(a: var StInt) =
+  a.imp.setOne
+
+func zero*[bits: static[int]](T: typedesc[StInt[bits]]): T =
   ## Returns the zero of the input type
-  discard
-  
-#[
-func one*[bits: static[int]](T: typedesc[StUint[bits]]): T {.inline.} =
+  result.setZero
+
+func one*[bits: static[int]](T: typedesc[StInt[bits]]): T =
   ## Returns the one of the input type
-  result.data = one(type result.data)
+  result.setOne
 
-import ./private/[int_addsub, uint_addsub]
+func high*[bits](_: typedesc[StInt[bits]]): StInt[bits] =
+  # The highest signed int has representation
+  # 0b0111_1111_1111_1111 ....
+  # so we only have to unset the most significant bit.
+  for i in 0 ..< result.limbs.len:
+    result[i] = high(Word)
+  result.clearSign
 
-func `+`*(x, y: SomeBigInteger): SomeBigInteger {.inline.} =
-  ## Integer addition
-  result.data = x.data + y.data
-func `+=`*(x: var SomeBigInteger, y: SomeBigInteger) {.inline.} =
-  ## Integer addition
-  x.data += y.data
-func `-`*(x, y: SomeBigInteger): SomeBigInteger {.inline.} =
-  ## Integer substraction
-  result.data = x.data - y.data
-func `-=`*(x: var SomeBigInteger, y: SomeBigInteger) {.inline.} =
-  ## Integer substraction
-  x.data -= y.data
+func low*[bits](_: typedesc[StInt[bits]]): StInt[bits] =
+  # The lowest signed int has representation
+  # 0b1000_0000_0000_0000 ....
+  # so we only have to set the most significant bit.
+  result.setZero
+  result.setSign
 
-import ./private/int_negabs
+{.pop.}
 
-func `-`*(x: StInt): StInt {.inline.} =
-  ## Returns true if input is zero
-  ## false otherwise
-  result.data = -x.data
+# Comparisons
+# --------------------------------------------------------
+{.push raises: [], inline, noinit, gcsafe.}
 
-func abs*(x: StInt): StInt {.inline.} =
-  ## Returns true if input is zero
-  ## false otherwise
-  result.data = abs(x.data)
+func isZero*(a: StInt): bool =
+  a.imp.isZero
 
-import ./private/[int_mul, uint_mul]
-
-func `*`*(x, y: SomeBigInteger): SomeBigInteger {.inline.} =
-  ## Integer multiplication
-  result.data = x.data * y.data
-
-import ./private/[int_div, uint_div]
-
-func `div`*(x, y: SomeBigInteger): SomeBigInteger {.inline.} =
-  ## Integer division
-  result.data = x.data div y.data
-func `mod`*(x, y: SomeBigInteger): SomeBigInteger {.inline.} =
-  ## Integer modulo
-  ## This returns the remainder of x / y.
-  ## i.e. x = y * quotient + remainder
-  result.data = x.data mod y.data
-func divmod*(x, y: SomeBigInteger): tuple[quot, rem: SomeBigInteger] {.inline.} =
-  ## Fused integer division and modulo
-  ## Return both the quotient and remainder
-  ## of x / y
-  (result.quot.data, result.rem.data) = divmod(x.data, y.data)
-
-import ./private/[int_comparison, uint_comparison]
-
-func `<`*(x, y: SomeBigInteger): bool {.inline.} =
-  ## Unsigned `less than` comparison
-  x.data < y.data
-func `<=`*(x, y: SomeBigInteger): bool {.inline.} =
-  ## Unsigned `less or equal` comparison
-  x.data <= y.data
-func `==`*(x, y: SomeBigInteger): bool {.inline.} =
+func `==`*(a, b: StInt): bool =
   ## Unsigned `equal` comparison
-  x.data == y.data
-export `<`, `<=`, `==` # Address Generic Instantiation too nested: https://github.com/status-im/nim-stint/pull/66#issuecomment-427557655
+  a.imp == b.imp
 
-# TODO these exports are needed for the SomeInteger versions - move to stew?
-export isZero, isOdd, isEven, isNegative
+func `<`*(a, b: StInt): bool =
+  ## Unsigned `less than` comparison
+  let
+    aSign = a.Sign
+    bSign = b.Sign
 
-func isZero*(x: SomeBigInteger): bool {.inline.} =
+  if aSign >= 0:
+    if bSign < 0:
+      return false
+  elif bSign >= 0:
+    return true
+
+  a.imp < b.imp
+
+func `<=`*(a, b: StInt): bool =
+  ## Unsigned `less or equal` comparison
+  not(b < a)
+
+func isOdd*(a: StInt): bool =
+  ## Returns true if input is off
+  ## false otherwise
+  bool(a[0] and 1)
+
+func isEven*(a: StInt): bool =
   ## Returns true if input is zero
   ## false otherwise
-  x.data.isZero
+  not a.isOdd()
 
-func isNegative*(x: StInt): bool {.inline.} =
-  ## Returns true if input is negative (< 0)
-  ## false otherwise
-  x.data.isNegative
+{.pop.}
 
-func isOdd*(x: SomeBigInteger): bool {.inline.} =
-  ## Returns true if input is zero
-  ## false otherwise
-  x.data.isOdd
+# Bitwise operations
+# --------------------------------------------------------
+{.push raises: [], inline, noinit, gcsafe.}
 
-func isEven*(x: SomeBigInteger): bool {.inline.} =
-  ## Returns true if input is zero
-  ## false otherwise
-  x.data.isEven
+func `not`*(a: StInt): StInt =
+  ## Bitwise complement of unsigned integer a
+  ## i.e. flips all bits of the input
+  result.imp.bitnot(a.imp)
 
-export isEven, isOdd
+func `or`*(a, b: StInt): StInt =
+  ## `Bitwise or` of numbers a and b
+  result.imp.bitor(a.imp, b.imp)
 
-import ./private/[int_bitwise_ops, uint_bitwise_ops]
+func `and`*(a, b: StInt): StInt =
+  ## `Bitwise and` of numbers a and b
+  result.imp.bitand(a.imp, b.imp)
 
-func `not`*(x: SomeBigInteger): SomeBigInteger {.inline.}=
-  ## Bitwise `not` i.e. flips all bits of the input
-  result.data = x.data.not
-func `or`*(x, y: SomeBigInteger): SomeBigInteger {.inline.}=
-  ## Bitwise `or`
-  result.data = x.data or y.data
-func `and`*(x, y: SomeBigInteger): SomeBigInteger {.inline.}=
-  ## Bitwise `and`
-  result.data = x.data and y.data
-func `xor`*(x, y: SomeBigInteger): SomeBigInteger {.inline.}=
-  ## Bitwise `xor`
-  result.data = x.data xor y.data
+func `xor`*(a, b: StInt): StInt =
+  ## `Bitwise xor` of numbers x and y
+  result.imp.bitxor(a.imp, b.imp)
 
-func `shr`*(x: SomeBigInteger, y: SomeInteger): SomeBigInteger {.inline.} =
-  result.data = x.data shr y
+{.pop.} # End noInit
 
-func `shl`*(x: SomeBigInteger, y: SomeInteger): SomeBigInteger {.inline.} =
-  result.data = x.data shl y
+{.push raises: [], inline, gcsafe.}
 
-import ./private/[int_highlow, uint_highlow]
+func `shr`*(a: StInt, k: SomeInteger): StInt =
+  ## Shift right by k bits, arithmetically
+  ## ~(~a >> k)
+  var tmp: type a
+  result.imp.bitnot(a.imp)
+  tmp.imp.shiftRight(result.imp, k)
+  result.imp.bitnot(tmp.imp)
 
-func high*[bits](_: typedesc[StInt[bits]]): StInt[bits] {.inline.} =
-  result.data = high(type result.data)
-func high*[bits](_: typedesc[StUint[bits]]): StUint[bits] {.inline.} =
-  result.data = high(type result.data)
+func `shl`*(a: StInt, k: SomeInteger): StInt =
+  ## Shift left by k bits
+  result.imp.shiftLeft(a.imp, k)
 
-func low*[bits](_: typedesc[StInt[bits]]): StInt[bits] {.inline.} =
-  result.data = low(type result.data)
-func low*[bits](_: typedesc[StUint[bits]]): StUint[bits] {.inline.} =
-  result.data = low(type result.data)
+{.pop.}
 
-import ./private/uint_exp, math
+# Addsub
+# --------------------------------------------------------
+{.push raises: [], inline, noinit, gcsafe.}
 
-func pow*(x: StUint, y: Natural): StUint {.inline.} =
-  ## Returns x raised at the power of y
-  when x.data is UintImpl:
-    result.data = x.data.pow(y)
-  else:
-    result.data = x.data ^ y
+#[
+func `+`*(a, b: StInt): StInt =
+  ## Addition for multi-precision unsigned int
+  result.sum(a, b)
 
-func pow*(x: StUint, y: StUint): StUint {.inline.} =
-  ## Returns x raised at the power of y
-  when x.data is UintImpl:
-    result.data = x.data.pow(y.data)
-  else:
-    result.data = x.data ^ y.data
-]#
\ No newline at end of file
+func `+=`*(a: var StInt, b: StInt) =
+  ## In-place addition for multi-precision unsigned int
+  a.sum(a, b)
+
+func `-`*(a, b: StInt): StInt =
+  ## Substraction for multi-precision unsigned int
+  result.diff(a, b)
+
+func `-=`*(a: var StInt, b: StInt) =
+  ## In-place substraction for multi-precision unsigned int
+  a.diff(a, b)
+
+func inc*(a: var StInt, w: Word = 1) =
+
+func `+`*(a: StInt, b: SomeUnsignedInt): StInt =
+  ## Addition for multi-precision unsigned int
+  ## with an unsigned integer
+  result.sum(a, Word(b))
+
+func `+=`*(a: var StInt, b: SomeUnsignedInt) =
+  ## In-place addition for multi-precision unsigned int
+  ## with an unsigned integer
+  a.inc(Word(b))
+]#
+
+{.pop.}
\ No newline at end of file
diff --git a/stint/io.nim b/stint/io.nim
index bd311bb..e85c5e5 100644
--- a/stint/io.nim
+++ b/stint/io.nim
@@ -46,32 +46,24 @@ template static_check_size(T: typedesc[SomeInteger], bits: static[int]) =
 func stuint*[T: SomeInteger](n: T, bits: static[int]): StUint[bits] {.inline.}=
   ## Converts an integer to an arbitrary precision integer.
   when sizeof(n) > sizeof(Word):
-    result.limbs[0] = Word(n and Word.high)  
+    result.limbs[0] = Word(n and Word.high)
     result.limbs[1] = Word(n shr WordBitWidth)
   else:
-    result.limbs[0] = Word(n)  
+    result.limbs[0] = Word(n)
 
-# func stint*[T: SomeInteger](n: T, bits: static[int]): StInt[bits] {.inline.}=
-#   ## Converts an integer to an arbitrary precision signed integer.
-#
-#   when result.data is IntImpl:
-#     static_check_size(T, bits)
-#     when T is SomeSignedInt:
-#       if n < 0:
-#         # TODO: when bits >= 128, cannot create from
-#         # low(int8-64)
-#         # see: status-im/nim-stint/issues/92
-#         assignLo(result.data, -n)
-#         result = -result
-#       else:
-#         assignLo(result.data, n)
-#     else:
-#       assignLo(result.data, n)
-#   else:
-#     result.data = (type result.data)(n)
+func stint*[T: SomeInteger](n: T, bits: static[int]): StInt[bits] {.inline.}=
+  ## Converts an integer to an arbitrary precision signed integer.
+  when T is SomeUnsignedInt:
+    result.imp = stuint(n, bits)
+  else:
+    if n < 0:
+      result.imp = stuint(-n, bits)
+      result.negate
+    else:
+      result.imp = stuint(n, bits)
 
-# func to*(a: SomeInteger, T: typedesc[Stint]): T =
-#   stint(a, result.bits)
+func to*(a: SomeInteger, T: typedesc[Stint]): T =
+  stint(a, result.bits)
 
 func to*(a: SomeUnsignedInt, T: typedesc[StUint]): T =
   stuint(a, result.bits)
@@ -83,9 +75,6 @@ func truncate*(num: StInt or StUint, T: typedesc[SomeInteger]): T {.inline.}=
   ## For signed result type, result is undefined if input does not fit in the target type.
   result = T(num.leastSignificantWord())
 
-func toInt*(num: StInt or StUint): int {.inline, deprecated:"Use num.truncate(int) instead".}=
-  num.truncate(int)
-
 func stuint*(a: StUint, bits: static[int]): StUint[bits] {.inline.} =
   ## unsigned int to unsigned int conversion
   ## smaller to bigger bits conversion will have the same value
@@ -307,46 +296,19 @@ func toString*[bits: static[int]](num: StUint[bits], radix: static[uint8] = 10):
 
   reverse(result)
 
-# func toString*[bits: static[int]](num: Stint[bits], radix: static[int8] = 10): string =
-#   ## Convert a Stint or StUint to string.
-#   ## In case of negative numbers:
-#   ##   - they are prefixed with "-" for base 10.
-#   ##   - if not base 10, they are returned raw in two-complement form.
+func toString*[bits: static[int]](num: StInt[bits], radix: static[int8] = 10): string =
+  ## Convert a Stint or StUint to string.
+  ## In case of negative numbers:
+  ##   - they are prefixed with "-" for base 10.
+  ##   - if not base 10, they are returned raw in two-complement form.
+  let isNeg = num.isNegative
+  if radix == 10 and isNeg:
+    "-" & toString(num.neg.imp, radix)
+  else:
+    toString(num.imp, radix)
 
-#   static: doAssert (radix >= 2) and radix <= 16, "Only base from 2..16 are supported"
-#   # TODO: use static[range[2 .. 16]], not supported at the moment (2018-04-26)
-
-#   const hexChars = "0123456789abcdef"
-#   const base = radix.int8.StUint(bits)
-
-#   result = ""
-
-#   type T = StUint[bits]
-#   let isNeg = num.isNegative
-#   let num = convert[T](if radix == 10 and isNeg: -num
-#             else: num)
-
-#   var (q, r) = divmod(num, base)
-
-#   while true:
-#     when bitsof(r.data) <= 64:
-#       result.add hexChars[r.data.int]
-#     else:
-#       result.add hexChars[r.truncate(int)]
-#     if q.isZero:
-#       break
-#     (q, r) = divmod(q, base)
-
-#   if isNeg and radix == 10:
-#     result.add '-'
-
-#   reverse(result)
-
-# func `$`*(num: Stint or StUint): string {.inline.}=
-#   when num.data is SomeInteger:
-#     $num.data
-#   else:
-#     toString(num, 10)
+func `$`*(num: StInt or StUint): string {.inline.}=
+  toString(num, 10)
 
 func toHex*[bits: static[int]](num: StInt[bits] or StUint[bits]): string {.inline.}=
   ## Convert to a hex string.
diff --git a/stint/private/datatypes.nim b/stint/private/datatypes.nim
index 569245c..b485ab0 100644
--- a/stint/private/datatypes.nim
+++ b/stint/private/datatypes.nim
@@ -40,7 +40,7 @@ type
   StInt*[bits: static[int]] = object
     ## Stack-based integer
     ## Signed
-    limbs*: array[bits.wordsRequired, Word]
+    imp*: StUint[bits]
 
   # {.borrow: `.`.} only works with nim-devel
   # StInt*[bits: static[int]] {.borrow: `.`.} = distinct StUint[bits]
@@ -94,6 +94,10 @@ func usedBitsAndWords*(a: openArray[Word]): tuple[bits, words: int] =
 # Accessors
 # --------------------------------------------------------
 
+template limbs*(a: StInt): untyped =
+  # TODO: remove this when we switch to borrow `.`
+  a.imp.limbs
+  
 template `[]`*(a: SomeBigInteger, i: SomeInteger or BackwardsIndex): Word =
   a.limbs[i]
 
diff --git a/stint/private/int_addsub.nim b/stint/private/int_addsub.nim
deleted file mode 100644
index b8d38e4..0000000
--- a/stint/private/int_addsub.nim
+++ /dev/null
@@ -1,49 +0,0 @@
-# Stint
-# Copyright 2018-2023 Status Research & Development GmbH
-# Licensed under either of
-#
-#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
-#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
-#
-# at your option. This file may not be copied, modified, or distributed except according to those terms.
-
-import
-  ./datatypes, ./conversion, ./int_comparison,
-  ./uint_addsub, ./uint_comparison
-
-func `+`*(x, y: IntImpl): IntImpl {.inline.}=
-  # Addition for multi-precision signed int.
-  type SubTy = type x.hi
-  result.lo = x.lo + y.lo
-  result.hi = (result.lo < y.lo).toSubtype(SubTy) + x.hi + y.hi
-
-  when compileOption("boundChecks"):
-    if unlikely(
-      not(result.isNegative xor x.isNegative) or
-      not(result.isNegative xor y.isNegative)
-    ):
-      return
-    raise newException(OverflowDefect, "Addition overflow")
-
-func `+=`*(x: var IntImpl, y: IntImpl) {.inline.}=
-  ## In-place addition for multi-precision signed int.
-  x = x + y
-
-func `-`*(x, y: IntImpl): IntImpl {.inline.}=
-  # Substraction for multi-precision signed int.
-
-  type SubTy = type x.hi
-  result.lo = x.lo - y.lo
-  result.hi = x.hi - y.hi - (x.lo < y.lo).toSubtype(SubTy)
-
-  when compileOption("boundChecks"):
-    if unlikely(
-      not(result.isNegative xor x.isNegative) or
-      not(result.isNegative xor y.isNegative.not)
-    ):
-      return
-    raise newException(OverflowDefect, "Substraction underflow")
-
-func `-=`*(x: var IntImpl, y: IntImpl) {.inline.}=
-  ## In-place substraction for multi-precision signed int.
-  x = x - y
diff --git a/stint/private/int_bitwise_ops.nim b/stint/private/int_bitwise_ops.nim
deleted file mode 100644
index ab9bc5c..0000000
--- a/stint/private/int_bitwise_ops.nim
+++ /dev/null
@@ -1,72 +0,0 @@
-# Stint
-# Copyright 2018-2023 Status Research & Development GmbH
-# Licensed under either of
-#
-#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
-#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
-#
-# at your option. This file may not be copied, modified, or distributed except according to those terms.
-
-import  ./datatypes, ./bitops2_priv, ./uint_bitwise_ops, ./compiletime_cast
-
-func `not`*(x: IntImpl): IntImpl {.inline.}=
-  ## Bitwise complement of unsigned integer x
-  applyHiLo(x, `not`)
-
-func `or`*(x, y: IntImpl): IntImpl {.inline.}=
-  ## `Bitwise or` of numbers x and y
-  applyHiLo(x, y, `or`)
-
-func `and`*(x, y: IntImpl): IntImpl {.inline.}=
-  ## `Bitwise and` of numbers x and y
-  applyHiLo(x, y, `and`)
-
-func `xor`*(x, y: IntImpl): IntImpl {.inline.}=
-  ## `Bitwise xor` of numbers x and y
-  applyHiLo(x, y, `xor`)
-
-func `shl`*(x: IntImpl, y: SomeInteger): IntImpl {.inline.}=
-  ## Compute the `shift left` operation of x and y
-  # Note: inlining this poses codegen/aliasing issue when doing `x = x shl 1`
-
-  # TODO: would it be better to reimplement this with words iteration?
-  const halfSize: type(y) = bitsof(x) div 2
-  type HiType = type(result.hi)
-
-  if y == 0:
-    return x
-  elif y == halfSize:
-    result.hi = convert[HiType](x.lo)
-  elif y < halfSize:
-    # `shr` in this equation uses uint version
-    result.hi = (x.hi shl y) or convert[HiType](x.lo shr (halfSize - y))
-    result.lo = x.lo shl y
-  else:
-    result.hi = convert[HiType](x.lo shl (y - halfSize))
-
-template createShr(name, operator: untyped) =
-  template name(x, y: SomeInteger): auto =
-    operator(x, y)
-
-  func name*(x: IntImpl, y: SomeInteger): IntImpl {.inline.}=
-    ## Compute the `arithmetic shift right` operation of x and y
-    ## Similar to C standard, result is undefined if y is bigger
-    ## than the number of bits in x.
-    const halfSize: type(y) = bitsof(x) div 2
-    type LoType = type(result.lo)
-    if y == 0:
-      return x
-    elif y == halfSize:
-      result.lo = convert[LoType](x.hi)
-      result.hi = name(x.hi, halfSize-1)
-    elif y < halfSize:
-      result.lo = (x.lo shr y) or convert[LoType](x.hi shl (halfSize - y))
-      result.hi = name(x.hi, y)
-    else:
-      result.lo = convert[LoType](name(x.hi, (y - halfSize)))
-      result.hi = name(x.hi, halfSize-1)
-
-createShr(shrOfShr, `shr`)
-
-template `shr`*(a, b: typed): untyped =
-  shrOfShr(a, b)
diff --git a/stint/private/int_comparison.nim b/stint/private/int_comparison.nim
deleted file mode 100644
index 2f4adf9..0000000
--- a/stint/private/int_comparison.nim
+++ /dev/null
@@ -1,49 +0,0 @@
-# Stint
-# Copyright 2018 Status Research & Development GmbH
-# Licensed under either of
-#
-#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
-#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
-#
-# at your option. This file may not be copied, modified, or distributed except according to those terms.
-
-import  ./datatypes, ./uint_comparison
-
-func isZero*(n: SomeSignedInt): bool {.inline.} =
-  n == 0
-
-func isZero*(n: IntImpl): bool {.inline.} =
-  n.hi.isZero and n.lo.isZero
-
-func isNegative*(n: SomeSignedInt): bool {.inline.} =
-  n < 0
-
-func isNegative*(n: IntImpl): bool {.inline.} =
-  ## Returns true if a number is negative:
-  n.hi.isNegative
-
-func `<`*(x, y: IntImpl): bool {.inline.}=
-  # Lower comparison for multi-precision integers
-  x.hi < y.hi or
-    (x.hi == y.hi and x.lo < y.lo)
-
-func `==`*(x, y: IntImpl): bool {.inline.}=
-  # Equal comparison for multi-precision integers
-  x.hi == y.hi and x.lo == y.lo
-
-func `<=`*(x, y: IntImpl): bool {.inline.}=
-  # Lower or equal comparison for multi-precision integers
-  x.hi < y.hi or
-    (x.hi == y.hi and x.lo <= y.lo)
-
-func isOdd*(x: SomeSignedInt): bool {.inline.}=
-  bool(x and 1)
-
-func isEven*(x: SomeSignedInt): bool {.inline.}=
-  not x.isOdd
-
-func isEven*(x: IntImpl): bool {.inline.}=
-  x.lo.isEven
-
-func isOdd*(x: IntImpl): bool {.inline.}=
-  not x.isEven
diff --git a/stint/private/int_highlow.nim b/stint/private/int_highlow.nim
deleted file mode 100644
index 1337065..0000000
--- a/stint/private/int_highlow.nim
+++ /dev/null
@@ -1,27 +0,0 @@
-# Stint
-# Copyright 2018 Status Research & Development GmbH
-# Licensed under either of
-#
-#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
-#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
-#
-# at your option. This file may not be copied, modified, or distributed except according to those terms.
-
-import ./datatypes, ./int_bitwise_ops, ./initialization, ./uint_highlow, typetraits
-
-# XXX There's some Araq reason why this isn't part of the std lib..
-func high(T: typedesc[SomeUnsignedInt]): T =
-  not T(0)
-
-func high*[T, T2](_: typedesc[IntImpl[T, T2]]): IntImpl[T, T2] {.inline.}=
-  # The highest signed int has representation
-  # 0b0111_1111_1111_1111 ....
-  # so we only have to unset the most significant bit.
-  result.hi = high(type result.hi)
-  result.lo = high(type result.lo)
-
-func low*[T, T2](_: typedesc[IntImpl[T, T2]]): IntImpl[T, T2] {.inline.}=
-  # The lowest signed int has representation
-  # 0b1000_0000_0000_0000 ....
-  # so we only have to set the most significant bit.
-  not high(IntImpl[T, T2])
diff --git a/stint/private/int_negabs.nim b/stint/private/int_negabs.nim
deleted file mode 100644
index 8803123..0000000
--- a/stint/private/int_negabs.nim
+++ /dev/null
@@ -1,29 +0,0 @@
-# Stint
-# Copyright 2018 Status Research & Development GmbH
-# Licensed under either of
-#
-#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
-#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
-#
-# at your option. This file may not be copied, modified, or distributed except according to those terms.
-
-import
-  ./datatypes,
-  ./initialization, ./int_highlow,
-  ./int_addsub, ./int_comparison, ./int_bitwise_ops
-
-func `-`*(x: IntImpl): IntImpl {.inline.}=
-  # Negate a multi-precision signed int.
-
-  when compileOption("boundChecks"):
-    if unlikely(x == low(type x)):
-      raise newException(OverflowError, "The lowest negative number cannot be negated")
-
-  result = not x
-  result += one(type x)
-
-func abs*[T: IntImpl](x: T): T {.inline.}=
-  ## Returns the absolute value of a signed int.
-
-  result =  if x.isNegative: -x
-            else: x
diff --git a/stint/private/uint_div.nim b/stint/private/uint_div.nim
index c0a0798..b033a4c 100644
--- a/stint/private/uint_div.nim
+++ b/stint/private/uint_div.nim
@@ -164,7 +164,7 @@ func divRem*(
   let rLen = bLen
 
   if unlikely(bBits == 0):
-    raise newException(DivByZeroError, "You attempted to divide by zero")
+    raise newException(DivByZeroDefect, "You attempted to divide by zero")
 
   if aBits < bBits:
     # if a uses less bits than b,
diff --git a/tests/test_helpers.nim b/tests/test_helpers.nim
index f3264a5..0c5fe55 100644
--- a/tests/test_helpers.nim
+++ b/tests/test_helpers.nim
@@ -5,5 +5,6 @@ template ctCheck*(cond: untyped) =
   doAssert(cond)
 
 template ctTest*(name: string, body: untyped) =
-  body
-  echo "[OK] compile time ", name
+  block:
+    body
+    echo "[OK] compile time ", name
diff --git a/tests/test_int_signedness.nim b/tests/test_int_signedness.nim
new file mode 100644
index 0000000..8e78a12
--- /dev/null
+++ b/tests/test_int_signedness.nim
@@ -0,0 +1,116 @@
+# Stint
+# Copyright 2018-2023 Status Research & Development GmbH
+# Licensed under either of
+#
+#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+#
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+import ../stint, unittest, test_helpers
+
+#[
+template chkAddition(chk, a, b, c, bits: untyped) =
+  block:
+    let x = stuint(a, bits)
+    let y = stuint(b, bits)
+    chk x + y == stuint(c, bits)
+]#
+
+template testSignedness(chk, tst: untyped) =
+  tst "positive sign":
+    let a = stint(1, 128)
+    chk a.sign > 0
+    chk a.isNegative == false
+
+    let b = stint(uint32.high, 128)
+    chk b.sign > 0
+    chk b.isNegative == false
+
+    let c = stint(uint64.high, 128)
+    chk c.sign > 0
+    chk c.isNegative == false
+
+    let aa = stint(1, 256)
+    chk aa.sign > 0
+    chk aa.isNegative == false
+
+    let bb = stint(uint32.high, 256)
+    chk bb.sign > 0
+    chk bb.isNegative == false
+
+    let cc = stint(uint64.high, 256)
+    chk cc.sign > 0
+    chk cc.isNegative == false
+
+    var zz: StInt[128]
+    zz.setOne
+    chk zz.sign > 0
+    chk zz.isNegative == false
+
+    let yy = StInt[128].one
+    chk yy.sign > 0
+    chk yy.isNegative == false
+
+  tst "zero sign":
+    let a = stint(0, 128)
+    chk a.sign == 0
+    chk a.isNegative == false
+
+    let aa = stint(0, 256)
+    chk aa.sign == 0
+    chk aa.isNegative == false
+
+    var zz: StInt[128]
+    zz.setZero
+    chk zz.sign == 0
+    chk zz.isNegative == false
+
+    let yy = StInt[128].zero
+    chk yy.sign == 0
+    chk yy.isNegative == false
+
+  tst "negative sign":
+    let a = stint(-1, 128)
+    chk a.sign < 0
+    chk a.isNegative == true
+
+    let aa = stint(-1, 256)
+    chk aa.sign < 0
+    chk aa.isNegative == true
+
+    let zz = -1.i128
+    chk zz.sign < 0
+    chk zz.isNegative == true
+
+    let yy = -1.i256
+    chk yy.sign < 0
+    chk yy.isNegative == true
+
+  tst "abs":
+    let a = -1.i128
+    let aa = a.abs
+    chk aa == 1.i128
+
+    let b = -1.i256
+    let bb = b.abs
+    chk bb == 1.i256
+
+  tst "negate":
+    var a = -1.i128
+    a.negate
+    chk a == 1.i128
+
+    var b = -1.i256
+    b.negate
+    chk b == 1.i256
+
+    let c = -1.i256
+    let d = -c
+    chk d == 1.i256
+
+static:
+  testSignedness(ctCheck, ctTest)
+
+suite "Signed integer signedness":
+  testSignedness(check, test)