diff --git a/library/constant_time.c b/library/constant_time.c
index 20e215a..86cc066 100644
--- a/library/constant_time.c
+++ b/library/constant_time.c
@@ -140,7 +140,7 @@
             unsigned char next    = buf[n+1];
             buf[n] = mbedtls_ct_uint_if(no_op, current, next);
         }
-        buf[total-1] = mbedtls_ct_uint_if0(no_op, buf[total-1]);
+        buf[total-1] = mbedtls_ct_uint_if_else_0(no_op, buf[total-1]);
     }
 }