diff --git a/media/libstagefright/DRMExtractor.cpp b/media/libstagefright/DRMExtractor.cpp
index 63cb430..9cb6e86 100644
--- a/media/libstagefright/DRMExtractor.cpp
+++ b/media/libstagefright/DRMExtractor.cpp
@@ -186,7 +186,8 @@
 
             srcOffset += mNALLengthSize;
 
-            if (srcOffset + nalLength > len) {
+            size_t end = srcOffset + nalLength;
+            if (end > len || end < srcOffset) {
                 if (decryptedDrmBuffer.data) {
                     delete [] decryptedDrmBuffer.data;
                     decryptedDrmBuffer.data = NULL;