diff --git a/libavcodec/ratecontrol.c b/libavcodec/ratecontrol.c
index 97438f6598..d289a19cb6 100644
--- a/libavcodec/ratecontrol.c
+++ b/libavcodec/ratecontrol.c
@@ -66,7 +66,7 @@ int ff_rate_control_init(MpegEncContext *s)
 {
     RateControlContext *rcc= &s->rc_context;
     int i;
-    char *error = NULL;
+    const char *error = NULL;
     static const char *const_names[]={
         "PI",
         "E",