diff --git a/crypto/fipsmodule/bn/div.c b/crypto/fipsmodule/bn/div.c
index 42c124c..6f850d9 100644
--- a/crypto/fipsmodule/bn/div.c
+++ b/crypto/fipsmodule/bn/div.c
@@ -481,7 +481,7 @@
   if (ret == NULL ||
       !BN_copy(ret, bn) ||
       !bn_resize_words(ret, width)) {
-    return 0;
+    return NULL;
   }
   return ret;
 }