diff --git a/src/dsp/enc_sse2.c b/src/dsp/enc_sse2.c
index 118ed70a..b046761d 100644
--- a/src/dsp/enc_sse2.c
+++ b/src/dsp/enc_sse2.c
@@ -12,6 +12,7 @@
 #include "./dsp.h"
 
 #if defined(WEBP_USE_SSE2)
+#include <stdlib.h>  // for abs()
 #include <emmintrin.h>
 
 #include "../enc/vp8enci.h"