diff --git a/media/libstagefright/MPEG4Extractor.cpp b/media/libstagefright/MPEG4Extractor.cpp
index 56bd875..9f257f7 100644
--- a/media/libstagefright/MPEG4Extractor.cpp
+++ b/media/libstagefright/MPEG4Extractor.cpp
@@ -1772,7 +1772,7 @@
                 ALOGV("chunk_data_size = %lld and data_offset = %lld",
                         chunk_data_size, data_offset);
 
-                if (chunk_data_size >= SIZE_MAX - 1) {
+                if (chunk_data_size < 0 || static_cast<uint64_t>(chunk_data_size) >= SIZE_MAX - 1) {
                     return ERROR_MALFORMED;
                 }
                 sp<ABuffer> buffer = new ABuffer(chunk_data_size + 1);