diff --git a/enc/encode.cc b/enc/encode.cc
index f46a1c9..fb6aafa 100644
--- a/enc/encode.cc
+++ b/enc/encode.cc
@@ -629,7 +629,7 @@ int BrotliCompressWithCustomDictionary(size_t dictsize, const uint8_t* dict,
                                        BrotliIn* in, BrotliOut* out) {
   size_t in_bytes = 0;
   size_t out_bytes = 0;
-  uint8_t* output;
+  uint8_t* output = NULL;
   bool final_block = false;
   BrotliCompressor compressor(params);
   if (dictsize != 0) compressor.BrotliSetCustomDictionary(dictsize, dict);