diff --git a/library/rsa.c b/library/rsa.c
index 2338264..222cb26 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -761,7 +761,7 @@
     for( i = 0; i < ilen - 2 * hlen - 2; i++ )
     {
         pad_done |= p[i];
-        pad_len += ( pad_done == 0 );
+        pad_len += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1;
     }
 
     p += pad_len;
@@ -835,8 +835,8 @@
          * (minus one, for the 00 byte) */
         for( i = 0; i < ilen - 3; i++ )
         {
-            pad_done |= ( p[i] == 0 );
-            pad_count += ( pad_done == 0 );
+            pad_done  |= ((p[i] | (unsigned char)-p[i]) >> 7) ^ 1;
+            pad_count += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1;
         }
 
         p += pad_count;