diff --git a/media/libstagefright/MPEG4Writer.cpp b/media/libstagefright/MPEG4Writer.cpp
index 66c4ffd..4681abd 100644
--- a/media/libstagefright/MPEG4Writer.cpp
+++ b/media/libstagefright/MPEG4Writer.cpp
@@ -3030,8 +3030,6 @@
     mOwner->writeInt16(0x18);        // depth
     mOwner->writeInt16(-1);          // predefined
 
-    CHECK_LT(23 + mCodecSpecificDataSize, 128);
-
     if (!strcasecmp(MEDIA_MIMETYPE_VIDEO_MPEG4, mime)) {
         writeMp4vEsdsBox();
     } else if (!strcasecmp(MEDIA_MIMETYPE_VIDEO_H263, mime)) {
@@ -3151,6 +3149,10 @@
 void MPEG4Writer::Track::writeMp4vEsdsBox() {
     CHECK(mCodecSpecificData);
     CHECK_GT(mCodecSpecificDataSize, 0);
+
+    // Make sure all sizes encode to a single byte.
+    CHECK_LT(23 + mCodecSpecificDataSize, 128);
+
     mOwner->beginBox("esds");
 
     mOwner->writeInt32(0);    // version=0, flags=0