diff --git a/stint/modular_arithmetic.nim b/stint/modular_arithmetic.nim
index e39ec68..a7c9d30 100644
--- a/stint/modular_arithmetic.nim
+++ b/stint/modular_arithmetic.nim
@@ -7,7 +7,7 @@
 #
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ./intops
+import ./intops, private/datatypes
 
 func addmod_internal(a, b, m: Stuint): Stuint {.inline.}=
   ## Modular addition
@@ -90,7 +90,7 @@ func addmod*(a, b, m: Stuint): Stuint =
 
   result = addmod_internal(a_m, b_m, m)
 
-proc submod*(a, b, m: Stuint): Stuint =
+func submod*(a, b, m: Stuint): Stuint =
   ## Modular substraction
 
   let a_m = if a < m: a
@@ -110,9 +110,16 @@ func mulmod*(a, b, m: Stuint): Stuint =
 
   result = mulmod_internal(a_m, b_m, m)
 
-proc powmod*(a, b, m: Stuint): Stuint =
+func powmod*[T](a, b, m: T): T =
   ## Modular exponentiation
 
+  when nimvm:
+    doAssert false, "cannot use powmod at compile-time"
+  else:
+    # we need this ugly branch
+    # because of nim-lang/Nim#12517
+    discard
+
   let a_m = if a < m: a
             else: a mod m
 
diff --git a/tests/test_uint_modular_arithmetic.nim b/tests/test_uint_modular_arithmetic.nim
index ed96d13..749b1be 100644
--- a/tests/test_uint_modular_arithmetic.nim
+++ b/tests/test_uint_modular_arithmetic.nim
@@ -100,41 +100,46 @@ template testModArith(chk, tst: untyped) =
     chkMulMod(chk, "1", "FFFFFFFFFFFFFFFF", "C", "3", 128)
     chkMulMod(chk, "1", "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", "C", "3", 128)
 
-  tst "powmod":
-    chkPowMod(chk, "C", "3", "C", "0", 8)
-    chkPowMod(chk, "1", "3", "C", "1", 8)
-    chkPowMod(chk, "1", "FF", "C", "1", 8)
-    chkPowMod(chk, "FF", "3", "C", "3", 8)
+  # TODO: bug #98
+  when nimvm:
+    # this ugly branch needed due to nim-lang/Nim#12518
+    discard
+  else:
+    tst "powmod":
+      chkPowMod(chk, "C", "3", "C", "0", 8)
+      chkPowMod(chk, "1", "3", "C", "1", 8)
+      chkPowMod(chk, "1", "FF", "C", "1", 8)
+      chkPowMod(chk, "FF", "3", "C", "3", 8)
 
-    chkPowMod(chk, "C", "3", "C", "0", 16)
-    chkPowMod(chk, "1", "3", "C", "1", 16)
-    chkPowMod(chk, "1", "FF", "C", "1", 16)
-    chkPowMod(chk, "FF", "3", "C", "3", 16)
-    chkPowMod(chk, "FFFF", "3", "C", "3", 16)
+      chkPowMod(chk, "C", "3", "C", "0", 16)
+      chkPowMod(chk, "1", "3", "C", "1", 16)
+      chkPowMod(chk, "1", "FF", "C", "1", 16)
+      chkPowMod(chk, "FF", "3", "C", "3", 16)
+      chkPowMod(chk, "FFFF", "3", "C", "3", 16)
 
-    chkPowMod(chk, "C", "3", "C", "0", 32)
-    chkPowMod(chk, "1", "3", "C", "1", 32)
-    chkPowMod(chk, "1", "FF", "C", "1", 32)
-    chkPowMod(chk, "FF", "3", "C", "3", 32)
-    chkPowMod(chk, "FFFF", "3", "C", "3", 32)
-    chkPowMod(chk, "FFFFFFFF", "3", "C", "3", 32)
+      chkPowMod(chk, "C", "3", "C", "0", 32)
+      chkPowMod(chk, "1", "3", "C", "1", 32)
+      chkPowMod(chk, "1", "FF", "C", "1", 32)
+      chkPowMod(chk, "FF", "3", "C", "3", 32)
+      chkPowMod(chk, "FFFF", "3", "C", "3", 32)
+      chkPowMod(chk, "FFFFFFFF", "3", "C", "3", 32)
 
-    chkPowMod(chk, "C", "3", "C", "0", 64)
-    chkPowMod(chk, "1", "3", "C", "1", 64)
-    chkPowMod(chk, "1", "FF", "C", "1", 64)
-    chkPowMod(chk, "FF", "3", "C", "3", 64)
-    chkPowMod(chk, "FFFF", "3", "C", "3", 64)
-    chkPowMod(chk, "FFFFFFFF", "3", "C", "3", 64)
-    chkPowMod(chk, "FFFFFFFFFFFFFFFF", "3", "C", "3", 64)
+      chkPowMod(chk, "C", "3", "C", "0", 64)
+      chkPowMod(chk, "1", "3", "C", "1", 64)
+      chkPowMod(chk, "1", "FF", "C", "1", 64)
+      chkPowMod(chk, "FF", "3", "C", "3", 64)
+      chkPowMod(chk, "FFFF", "3", "C", "3", 64)
+      chkPowMod(chk, "FFFFFFFF", "3", "C", "3", 64)
+      chkPowMod(chk, "FFFFFFFFFFFFFFFF", "3", "C", "3", 64)
 
-    chkPowMod(chk, "C", "3", "C", "0", 128)
-    chkPowMod(chk, "1", "3", "C", "1", 128)
-    chkPowMod(chk, "1", "FF", "C", "1", 128)
-    chkPowMod(chk, "FF", "3", "C", "3", 128)
-    chkPowMod(chk, "FFFF", "3", "C", "3", 128)
-    chkPowMod(chk, "FFFFFFFF", "3", "C", "3", 128)
-    chkPowMod(chk, "FFFFFFFFFFFFFFFF", "3", "C", "3", 128)
-    chkPowMod(chk, "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", "3", "C", "3", 128)
+      chkPowMod(chk, "C", "3", "C", "0", 128)
+      chkPowMod(chk, "1", "3", "C", "1", 128)
+      chkPowMod(chk, "1", "FF", "C", "1", 128)
+      chkPowMod(chk, "FF", "3", "C", "3", 128)
+      chkPowMod(chk, "FFFF", "3", "C", "3", 128)
+      chkPowMod(chk, "FFFFFFFF", "3", "C", "3", 128)
+      chkPowMod(chk, "FFFFFFFFFFFFFFFF", "3", "C", "3", 128)
+      chkPowMod(chk, "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", "3", "C", "3", 128)
 
 static:
   testModArith(ctCheck, ctTest)