diff --git a/libavformat/psxstr.c b/libavformat/psxstr.c
index 49b34413a6..86fba163ea 100644
--- a/libavformat/psxstr.c
+++ b/libavformat/psxstr.c
@@ -64,7 +64,7 @@ typedef struct StrDemuxContext {
     StrChannel channels[32];
 } StrDemuxContext;
 
-static const char sync_header[12] = {0x00,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0x00};
+static const uint8_t sync_header[12] = {0x00,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0x00};
 
 static int str_probe(AVProbeData *p)
 {