diff --git a/libao2/ao_pcm.c b/libao2/ao_pcm.c
index 857b4df77e..34ffa005e6 100644
--- a/libao2/ao_pcm.c
+++ b/libao2/ao_pcm.c
@@ -1,7 +1,9 @@
+#include "config.h"
+
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
-#include "config.h"
 #include "bswap.h"
 #include "afmt.h"
 #include "audio_out.h"
diff --git a/libao2/ao_plugin.c b/libao2/ao_plugin.c
index 4806228d67..53b6bde915 100644
--- a/libao2/ao_plugin.c
+++ b/libao2/ao_plugin.c
@@ -1,7 +1,8 @@
+#include "../config.h"
+
 #include <stdio.h>
 #include <stdlib.h>
-
-#include "../config.h"
+#include <string.h>
 
 #include "afmt.h"
 #include "audio_out.h"
diff --git a/libao2/pl_delay.c b/libao2/pl_delay.c
index 3d0f457dc4..32bec035eb 100644
--- a/libao2/pl_delay.c
+++ b/libao2/pl_delay.c
@@ -7,6 +7,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include "audio_out.h"
 #include "audio_plugin.h"
diff --git a/libao2/pl_format.c b/libao2/pl_format.c
index 932b2e014a..93c3d701cd 100644
--- a/libao2/pl_format.c
+++ b/libao2/pl_format.c
@@ -9,6 +9,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 #include <inttypes.h>
 
diff --git a/libao2/pl_surround.c b/libao2/pl_surround.c
index fcb3be23bf..dad0cbafcf 100644
--- a/libao2/pl_surround.c
+++ b/libao2/pl_surround.c
@@ -38,6 +38,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
 #include "audio_out.h"