diff --git a/library/md5.c b/library/md5.c
index d2b634f..4eea653 100644
--- a/library/md5.c
+++ b/library/md5.c
@@ -458,8 +458,8 @@
     { "message digest" },
     { "abcdefghijklmnopqrstuvwxyz" },
     { "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789" },
-    { "12345678901234567890123456789012345678901234567890123456789012"
-      "345678901234567890" }
+    { ("12345678901234567890123456789012345678901234567890123456789012"
+      "345678901234567890") }
 };
 
 static const size_t md5_test_buflen[7] =