diff --git a/library/md4.c b/library/md4.c
index 37056d9..97cb5f0 100644
--- a/library/md4.c
+++ b/library/md4.c
@@ -199,7 +199,7 @@
     size_t fill;
     uint32_t left;
 
-    if( ilen <= 0 )
+    if( ilen == 0 )
         return;
 
     left = ctx->total[0] & 0x3F;