diff --git a/libavutil/avstring.c b/libavutil/avstring.c
index b77b1605ab..02af970812 100644
--- a/libavutil/avstring.c
+++ b/libavutil/avstring.c
@@ -24,6 +24,7 @@
 #include <string.h>
 #include <ctype.h>
 #include "avstring.h"
+#include "mem.h"
 
 int av_strstart(const char *str, const char *pfx, const char **ptr)
 {
diff --git a/libavutil/avstring.h b/libavutil/avstring.h
index 98d5235b65..b8203f372f 100644
--- a/libavutil/avstring.h
+++ b/libavutil/avstring.h
@@ -22,7 +22,6 @@
 #define AVUTIL_AVSTRING_H
 
 #include <stddef.h>
-#include "mem.h"
 
 /**
  * Return non-zero if pfx is a prefix of str. If it is, *ptr is set to