diff --git a/library/aes.c b/library/aes.c
index c355bfc..2f52202 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -888,7 +888,7 @@
                        const unsigned char *input,
                        unsigned char *output )
 {
-    int c, i, cb;
+    int c, i;
     size_t n = *nc_off;
 
     while( length-- )
@@ -896,12 +896,9 @@
         if( n == 0 ) {
             aes_crypt_ecb( ctx, AES_ENCRYPT, nonce_counter, stream_block );
 
-            i = 15;
-            do {
-               nonce_counter[i]++;
-               cb = nonce_counter[i] == 0;
-            } while( i-- && cb );
-
+            for( i = 16; i > 0; i-- )
+                if( ++nonce_counter[i - 1] != 0 )
+                    break;
         }
         c = *input++;
         *output++ = (unsigned char)( c ^ stream_block[n] );