diff --git a/src/enc/histogram.h b/src/enc/histogram.h
index e997a9cc..adb16c01 100644
--- a/src/enc/histogram.h
+++ b/src/enc/histogram.h
@@ -14,10 +14,6 @@
 #ifndef WEBP_ENC_HISTOGRAM_H_
 #define WEBP_ENC_HISTOGRAM_H_
 
-#include <assert.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <stdio.h>
 #include <string.h>
 
 #include "./backward_references.h"