diff --git a/library/sha1.c b/library/sha1.c
index 4b2d063..da69a8f 100644
--- a/library/sha1.c
+++ b/library/sha1.c
@@ -252,7 +252,7 @@
     size_t fill;
     uint32_t left;
 
-    if( ilen <= 0 )
+    if( ilen == 0 )
         return;
 
     left = ctx->total[0] & 0x3F;