diff --git a/libavcodec/aarch64/h264idct_neon.S b/libavcodec/aarch64/h264idct_neon.S
index e9f5b18af0..825ec49f8c 100644
--- a/libavcodec/aarch64/h264idct_neon.S
+++ b/libavcodec/aarch64/h264idct_neon.S
@@ -264,6 +264,7 @@ endfunc
 
 function ff_h264_idct8_add_neon, export=1
         movi            v19.8H,   #0
+        sxtw            x2,       w2
         ld1             {v24.8H, v25.8H}, [x1]
         st1             {v19.8H},  [x1],   #16
         st1             {v19.8H},  [x1],   #16