diff --git a/lib/nimbase.h b/lib/nimbase.h
index d25c4dad070e8..8c1c3d8a5512c 100644
--- a/lib/nimbase.h
+++ b/lib/nimbase.h
@@ -549,22 +549,24 @@ typedef int Nim_and_C_compiler_disagree_on_target_architecture[sizeof(NI) == siz
 #define nimModInt(a, b, res) (((*res) = (a) % (b)), 0)
 #define nimModInt64(a, b, res) (((*res) = (a) % (b)), 0)
 
-/* these exist because we cannot have .compilerProcs that are importc'ed
-   by a different name */
-
-#define nimAddInt64(a, b, res) __builtin_saddll_overflow(a, b, (long long int*)res)
-#define nimSubInt64(a, b, res) __builtin_ssubll_overflow(a, b, (long long int*)res)
-#define nimMulInt64(a, b, res) __builtin_smulll_overflow(a, b, (long long int*)res)
-
-#if NIM_INTBITS == 32
-  #define nimAddInt(a, b, res) __builtin_sadd_overflow(a, b, res)
-  #define nimSubInt(a, b, res) __builtin_ssub_overflow(a, b, res)
-  #define nimMulInt(a, b, res) __builtin_smul_overflow(a, b, res)
-#else
-  /* map it to the 'long long' variant */
-  #define nimAddInt(a, b, res) __builtin_saddll_overflow(a, b, (long long int*)res)
-  #define nimSubInt(a, b, res) __builtin_ssubll_overflow(a, b, (long long int*)res)
-  #define nimMulInt(a, b, res) __builtin_smulll_overflow(a, b, (long long int*)res)
+#if !defined(_MSC_VER)
+  /* these exist because we cannot have .compilerProcs that are importc'ed
+    by a different name */
+
+  #define nimAddInt64(a, b, res) __builtin_saddll_overflow(a, b, (long long int*)res)
+  #define nimSubInt64(a, b, res) __builtin_ssubll_overflow(a, b, (long long int*)res)
+  #define nimMulInt64(a, b, res) __builtin_smulll_overflow(a, b, (long long int*)res)
+
+  #if NIM_INTBITS == 32
+    #define nimAddInt(a, b, res) __builtin_sadd_overflow(a, b, res)
+    #define nimSubInt(a, b, res) __builtin_ssub_overflow(a, b, res)
+    #define nimMulInt(a, b, res) __builtin_smul_overflow(a, b, res)
+  #else
+    /* map it to the 'long long' variant */
+    #define nimAddInt(a, b, res) __builtin_saddll_overflow(a, b, (long long int*)res)
+    #define nimSubInt(a, b, res) __builtin_ssubll_overflow(a, b, (long long int*)res)
+    #define nimMulInt(a, b, res) __builtin_smulll_overflow(a, b, (long long int*)res)
+  #endif
 #endif
 
 #endif /* NIMBASE_H */