diff --git a/src/uint_init.nim b/src/init.nim
similarity index 53%
rename from src/uint_init.nim
rename to src/init.nim
index 76358da..d013198 100644
--- a/src/uint_init.nim
+++ b/src/init.nim
@@ -33,3 +33,36 @@ func stuint*[T: SomeInteger](n: T, bits: static[int]): StUint[bits] {.inline.}=
         r_ptr[r_ptr[].len - 1] = n
   else:
     result.data = (type result.data)(n)
+
+func stint*[T: SomeInteger](n: T, bits: static[int]): StInt[bits] {.inline.}=
+
+  when result.data is UintImpl:
+    when getSize(n) > bits:
+      # To avoid a costly runtime check, we refuse storing into StUint types smaller
+      # than the input type.
+      raise newException(ValueError, "Input " & $n & " (" & $T &
+                                    ") cannot be stored in a multi-precision " &
+                                    $bits & "-bit integer." &
+                                    "\nUse a smaller input type instead. This is a compile-time check" &
+                                    " to avoid a costly run-time bit_length check at each StUint initialization.")
+    else:
+      let r_ptr = cast[ptr array[bits div (sizeof(T) * 8), T]](result.addr)
+      when system.cpuEndian == littleEndian:
+        # "Least significant byte are at the beginning"
+        if n < 0:
+          r_ptr[0] = -n
+          result = -result
+        else:
+          r_ptr[0] = n
+      else:
+        if n < 0:
+          r_ptr[r_ptr[].len - 1] = -n
+          result = -result
+        else:
+          r_ptr[r_ptr[].len - 1] = n
+  else:
+    if n < 0:
+      result.data = (type result.data)(-n)
+      result = -result
+    else:
+      result.data = (type result.data)(n)
diff --git a/src/int_public.nim b/src/int_public.nim
new file mode 100644
index 0000000..a71fd6e
--- /dev/null
+++ b/src/int_public.nim
@@ -0,0 +1,79 @@
+# Mpint
+# 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 ./private/datatypes, macros
+export StInt, IntImpl, intImpl # TODO remove the need to export intImpl and this macro
+
+type
+  Int128* = Stint[128]
+  Int256* = Stint[256]
+
+template make_conv(conv_name: untyped, size: int): untyped =
+  func `convname`*(n: SomeInteger): Stint[size] {.inline, noInit.}=
+    n.stint(size)
+
+make_conv(i128, 128)
+make_conv(i256, 256)
+
+template make_unary(op, ResultTy): untyped =
+  func `op`*(x: Stint): ResultTy {.noInit, inline.} =
+    when ResultTy is Stint:
+      result.data = op(x.data)
+    else:
+      op(x.data)
+  export op
+
+template make_binary(op, ResultTy): untyped =
+  func `op`*(x, y: Stint): ResultTy {.noInit, inline.} =
+    when ResultTy is Stint:
+      result.data = op(x.data, y.data)
+    else:
+      op(x.data, y.data)
+  export `op`
+
+template make_binary_inplace(op): untyped =
+  func `op`*(x: var Stint, y: Stint) {.inline.} =
+    op(x.data, y.data)
+  export op
+
+import ./private/int_addsubneg
+
+make_binary(`+`, Stint)
+make_binary_inplace(`+=`)
+make_unary(`-`, Stint)
+# make_binary(`-`, Stint)
+# make_binary_inplace(`-=`)
+
+# import ./private/int_mul
+# make_binary(`*`, Stint)
+
+# import ./private/int_div
+
+# make_binary(`div`, Stint)
+# make_binary(`mod`, Stint)
+# func divmod*(x, y: Stint): tuple[quot, rem: Stint] {.noInit, inline.} =
+#   (result.quot.data, result.rem.data) = divmod(x.data, y.data)
+
+import ./private/int_comparison
+
+make_binary(`<`, bool)
+make_binary(`<=`, bool)
+make_binary(`==`, bool)
+func isZero*(x: Stint): bool {.inline.} = isZero x.data
+
+import ./private/int_bitwise_ops
+
+make_unary(`not`, Stint)
+make_binary(`or`, Stint)
+make_binary(`and`, Stint)
+make_binary(`xor`, Stint)
+# proc `shr`*(x: Stint, y: SomeInteger): Stint {.noInit, inline, noSideEffect.} =
+#   result.data = x.data shr y
+# proc `shl`*(x: Stint, y: SomeInteger): Stint {.noInit, inline, noSideEffect.} =
+#   result.data = x.data shl y
diff --git a/src/private/bithacks.nim b/src/private/bithacks.nim
index a6d6d01..116451d 100644
--- a/src/private/bithacks.nim
+++ b/src/private/bithacks.nim
@@ -25,7 +25,7 @@ func countLeadingZeroBits*(n: UintImpl): int {.inline.} =
               n.lo.countLeadingZeroBits + maxHalfRepr
             else: hi_clz
 
-func msb*[T: SomeInteger](n: T): T =
+func msb*[T: SomeInteger](n: T): T {.inline.}=
   ## Returns the most significant bit of an integer.
 
   when T is int64 or (T is int and sizeof(int) == 8):
@@ -42,7 +42,7 @@ func msb*[T: SomeInteger](n: T): T =
   const msb_pos = sizeof(T) * 8 - 1
   result = T(cast[Uint](n) shr msb_pos)
 
-func msb*(n: IntImpl): auto =
+func msb*(n: IntImpl): auto {.inline.}=
   ## Returns the most significant bit of an arbitrary precision integer.
 
   result = msb most_significant_word(n)
diff --git a/src/private/datatypes.nim b/src/private/datatypes.nim
index 31799d1..96aa7fe 100644
--- a/src/private/datatypes.nim
+++ b/src/private/datatypes.nim
@@ -109,8 +109,6 @@ macro getSize*(x: typed): untyped =
 
 type
   # ### Private ### #
-  # If this is not in the same type section
-  # the compiler has trouble
   BaseUint* = UintImpl or SomeUnsignedInt
 
   UintImpl*[Baseuint] = object
@@ -120,6 +118,7 @@ type
       hi*, lo*: BaseUint
 
   IntImpl*[Baseuint] = object
+    # Ints are implemented in terms of uints
     when system.cpuEndian == littleEndian:
       lo*, hi*: BaseUint
     else:
diff --git a/src/private/initialization.nim b/src/private/initialization.nim
index 46ccd13..96d709e 100644
--- a/src/private/initialization.nim
+++ b/src/private/initialization.nim
@@ -40,3 +40,13 @@ func one*[T: BaseUint](_: typedesc[T]): T {.inline.}=
       r_ptr[0] = 1
     else:
       r_ptr[r_ptr[].len - 1] = 1
+
+func one*[T: IntImpl](_: typedesc[T]): T {.inline.}=
+  when T is SomeInteger:
+    result = T(1)
+  else:
+    let r_ptr = cast[ptr array[getSize(result) div 8, byte]](result.addr)
+    when system.cpuEndian == bigEndian:
+      r_ptr[0] = 1
+    else:
+      r_ptr[r_ptr[].len - 1] = 1
diff --git a/src/private/int_addsubneg.nim b/src/private/int_addsubneg.nim
new file mode 100644
index 0000000..6a68b5a
--- /dev/null
+++ b/src/private/int_addsubneg.nim
@@ -0,0 +1,26 @@
+# Mpint
+# 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
+
+func `+=`*(x: var IntImpl, y: IntImpl) {.inline.}=
+  ## In-place addition for multi-precision signed int
+
+  type SubTy = type x.lo
+  x.lo += y.lo
+  x.hi += (x.lo < y.lo).toSubtype(SubTy) + y.hi
+
+func `+`*(x, y: UintImpl): UintImpl {.noInit, inline.}=
+  # Addition for multi-precision signed int
+  result = x
+  result += y
+
+func `-`*[T: IntImpl](x: T): T {.noInit, inline.}=
+  result = not x
+  result += one(T)
diff --git a/src/private/int_bitwise_ops.nim b/src/private/int_bitwise_ops.nim
new file mode 100644
index 0000000..b363863
--- /dev/null
+++ b/src/private/int_bitwise_ops.nim
@@ -0,0 +1,31 @@
+# Mpint
+# 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, ./as_words
+
+
+func `not`*(x: IntImpl): IntImpl {.noInit, inline.}=
+  ## Bitwise complement of unsigned integer x
+  m_asWordsZip(result, x, ignoreEndianness = true):
+    result = not x
+
+func `or`*(x, y: IntImpl): IntImpl {.noInit, inline.}=
+  ## `Bitwise or` of numbers x and y
+  m_asWordsZip(result, x, y, ignoreEndianness = true):
+    result = x or y
+
+func `and`*(x, y: IntImpl): IntImpl {.noInit, inline.}=
+  ## `Bitwise and` of numbers x and y
+  m_asWordsZip(result, x, y, ignoreEndianness = true):
+    result = x and y
+
+func `xor`*(x, y: IntImpl): IntImpl {.noInit, inline.}=
+  ## `Bitwise xor` of numbers x and y
+  m_asWordsZip(result, x, y, ignoreEndianness = true):
+    result = x xor y
diff --git a/src/private/uint_mul.nim b/src/private/uint_mul.nim
index cf43162..041a7c4 100644
--- a/src/private/uint_mul.nim
+++ b/src/private/uint_mul.nim
@@ -115,7 +115,7 @@ func extPrecMul*[T](result: var UintImpl[UintImpl[T]], x, y: UintImpl[T]) =
   if result.lo.hi < z1.lo:
     result.hi += one(UintImpl[T])
 
-func `*`*[T](x, y: UintImpl[T]): UintImpl[T] {.inline.}=
+func `*`*[T](x, y: UintImpl[T]): UintImpl[T] {.inline, noInit.}=
   ## Multiplication for multi-precision unsigned uint
   #
   # For our representation, it is similar to school grade multiplication
diff --git a/src/mpint.nim b/src/stint.nim
similarity index 82%
rename from src/mpint.nim
rename to src/stint.nim
index b047a3b..5295369 100644
--- a/src/mpint.nim
+++ b/src/stint.nim
@@ -7,5 +7,5 @@
 #
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import  ./uint_public, ./uint_init
-export  uint_public, uint_init
+import  ./uint_public, ./int_public, ./init
+export  uint_public, int_public, init
diff --git a/tests/property_based.nim b/tests/property_based.nim
index 5cc884e..a2ec256 100644
--- a/tests/property_based.nim
+++ b/tests/property_based.nim
@@ -7,7 +7,7 @@
 #
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ../src/mpint, unittest, quicktest
+import ../src/stint, unittest, quicktest
 
 const itercount = 1000
 
diff --git a/tests/property_based_uint256.nim b/tests/property_based_uint256.nim
index 9b2efdc..a5d78f1 100644
--- a/tests/property_based_uint256.nim
+++ b/tests/property_based_uint256.nim
@@ -10,7 +10,7 @@
 
 # Requires "https://github.com/status-im/nim-ttmath#master"
 # Note that currently importing both Stint and TTMath will crash the compiler for unknown reason
-import ../src/mpint, unittest, quicktest, ttmath
+import ../src/stint, unittest, quicktest, ttmath
 
 const itercount = 1000
 
diff --git a/tests/test_int_comparison.nim b/tests/test_int_comparison.nim
new file mode 100644
index 0000000..36c4729
--- /dev/null
+++ b/tests/test_int_comparison.nim
@@ -0,0 +1,41 @@
+# Mpint
+# 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 ../src/stint, unittest
+
+suite "Signed int - Testing comparison operators":
+  let
+    a = 10'i16.stint(16)
+    b = 15'i16.stint(16)
+    c = 150'u16
+
+  test "< operator":
+    check:
+      a < b
+      not (a + b < b)
+      not (a + a + a < b + b)
+
+  test "<= operator":
+    check:
+      a <= b
+      not (a + b <= b)
+      a + a + a <= b + b
+
+  test "> operator":
+    check:
+      b > a
+      not (b > a + b)
+      not (b + b > a + a + a)
+
+  test ">= operator":
+    check:
+      b >= a
+      not (b >= a + b)
+      b + b >= a + a + a
+
diff --git a/tests/test_uint_addsub.nim b/tests/test_uint_addsub.nim
index 007be7b..e8c0e05 100644
--- a/tests/test_uint_addsub.nim
+++ b/tests/test_uint_addsub.nim
@@ -7,7 +7,7 @@
 #
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ../src/mpint, unittest
+import ../src/stint, unittest
 
 suite "Testing addition implementation":
   test "In-place addition gives expected result":
diff --git a/tests/test_uint_bitwise.nim b/tests/test_uint_bitwise.nim
index 0a782d9..39d2dba 100644
--- a/tests/test_uint_bitwise.nim
+++ b/tests/test_uint_bitwise.nim
@@ -7,7 +7,7 @@
 #
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ../src/mpint, unittest
+import ../src/stint, unittest
 
 suite "Testing bitwise operations":
   let a = 100'i16.stuint(16)
diff --git a/tests/test_uint_comparison.nim b/tests/test_uint_comparison.nim
index 373b831..34728f2 100644
--- a/tests/test_uint_comparison.nim
+++ b/tests/test_uint_comparison.nim
@@ -7,7 +7,7 @@
 #
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ../src/mpint, unittest
+import ../src/stint, unittest
 
 suite "Testing comparison operators":
   let
diff --git a/tests/test_uint_endianness.nim b/tests/test_uint_endianness.nim
index 00775d5..eea24f7 100644
--- a/tests/test_uint_endianness.nim
+++ b/tests/test_uint_endianness.nim
@@ -7,7 +7,7 @@
 #
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ../src/mpint, unittest
+import ../src/stint, unittest
 
 suite "Testing byte representation":
   test "Byte representation conforms to the platform endianness":
diff --git a/tests/test_uint_muldiv.nim b/tests/test_uint_muldiv.nim
index 01b13ba..5c331f0 100644
--- a/tests/test_uint_muldiv.nim
+++ b/tests/test_uint_muldiv.nim
@@ -7,7 +7,7 @@
 #
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ../src/mpint, unittest
+import ../src/stint, unittest
 
 suite "Testing multiplication implementation":
   test "Multiplication with result fitting in low half":