diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index 2b507d2..3db517d 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -336,7 +336,7 @@
          */
         aes_crypt_ecb( &ctx->aes_ctx, AES_ENCRYPT, ctx->counter, tmp );
 
-        use_len = (output_len > CTR_DRBG_BLOCKSIZE ) ? CTR_DRBG_BLOCKSIZE :
+        use_len = ( output_len > CTR_DRBG_BLOCKSIZE ) ? CTR_DRBG_BLOCKSIZE :
                                                        output_len;
         /*
          * Copy random block to destination