diff --git a/libpostproc/postprocess.c b/libpostproc/postprocess.c
index f6905de375..e52574c397 100644
--- a/libpostproc/postprocess.c
+++ b/libpostproc/postprocess.c
@@ -741,7 +741,7 @@ char *pp_help=
 "\n"
 ;
 
-pp_mode_t *pp_get_mode_by_name_and_quality(char *name, int quality)
+pp_mode_t *pp_get_mode_by_name_and_quality(const char *name, int quality)
 {
         char temp[GET_MODE_BUFFER_SIZE];
         char *p= temp;
diff --git a/libpostproc/postprocess.h b/libpostproc/postprocess.h
index 1109b2047e..e3ac29e2e4 100644
--- a/libpostproc/postprocess.h
+++ b/libpostproc/postprocess.h
@@ -56,7 +56,7 @@ void  pp_postprocess(uint8_t * src[3], int srcStride[3],
  * name is the string after "-pp" on the command line
  * quality is a number from 0 to PP_QUALITY_MAX
  */
-pp_mode_t *pp_get_mode_by_name_and_quality(char *name, int quality);
+pp_mode_t *pp_get_mode_by_name_and_quality(const char *name, int quality);
 void pp_free_mode(pp_mode_t *mode);
 
 pp_context_t *pp_get_context(int width, int height, int flags);