diff --git a/src/md/blake2.h b/src/md/blake2.h
index ad62f260e..ca390305e 100644
--- a/src/md/blake2.h
+++ b/src/md/blake2.h
@@ -137,8 +137,8 @@ extern "C" {
 
   /* Padded structs result in a compile-time error */
   enum {
-    BLAKE2_DUMMY_1 = 1/(sizeof(blake2s_param) == BLAKE2S_OUTBYTES),
-    BLAKE2_DUMMY_2 = 1/(sizeof(blake2b_param) == BLAKE2B_OUTBYTES)
+    BLAKE2_DUMMY_1 = 1/(int)(sizeof(blake2s_param) == BLAKE2S_OUTBYTES),
+    BLAKE2_DUMMY_2 = 1/(int)(sizeof(blake2b_param) == BLAKE2B_OUTBYTES)
   };
 
   /* Streaming API */