diff --git a/libmpcodecs/ad_hwac3.c b/libmpcodecs/ad_hwac3.c
index 1b6f2da335..229d5593af 100644
--- a/libmpcodecs/ad_hwac3.c
+++ b/libmpcodecs/ad_hwac3.c
@@ -15,6 +15,7 @@
 
 #include "mp_msg.h"
 #include "help_mp.h"
+#include "mpbswap.h"
 
 #include "ad_internal.h"
 
diff --git a/libmpcodecs/ad_liba52.c b/libmpcodecs/ad_liba52.c
index ca5b0db064..c9c7b9c69f 100644
--- a/libmpcodecs/ad_liba52.c
+++ b/libmpcodecs/ad_liba52.c
@@ -8,6 +8,7 @@
 
 #include "mp_msg.h"
 #include "help_mp.h"
+#include "mpbswap.h"
 
 #include "ad_internal.h"
 
diff --git a/mpbswap.h b/mpbswap.h
index f5b6601dcc..27cf7b69d5 100644
--- a/mpbswap.h
+++ b/mpbswap.h
@@ -2,5 +2,6 @@
 #define MPBSWAP_H
 
 #include "libavutil/bswap.h"
+void swab(const void *from, void *to, ssize_t n);
 
 #endif /* MPBSWAP_H */