diff --git a/wolfcrypt/src/tfm.c b/wolfcrypt/src/tfm.c
index 56fb5993e..4098ebfd9 100644
--- a/wolfcrypt/src/tfm.c
+++ b/wolfcrypt/src/tfm.c
@@ -1027,7 +1027,13 @@ void fp_mod_2d(fp_int *a, int b, fp_int *c)
     c->dp[x] = 0;
   }
   /* clear the digit that is not completely outside/inside the modulus */
-  c->dp[b / DIGIT_BIT] &= ~((fp_digit)0) >> (DIGIT_BIT - b);
+  x = DIGIT_BIT - b;
+  if (x > 0) {
+    c->dp[b / DIGIT_BIT] &= ~((fp_digit)0) >> x;
+  }
+  else
+    c->dp[b / DIGIT_BIT] &= ~((fp_digit)0) << -x;
+
   fp_clamp (c);
 }