diff --git a/pipi/pipi.h b/pipi/pipi.h
index 3ff965a..c177b8e 100644
--- a/pipi/pipi.h
+++ b/pipi/pipi.h
@@ -237,7 +237,7 @@ __extern int pipi_get_image_histogram(pipi_image_t *, pipi_histogram_t *, int);
 __extern int pipi_free_histogram(pipi_histogram_t*);
 __extern int pipi_render_histogram(pipi_image_t *, pipi_histogram_t*, int);
 
-__extern pipi_sequence_t *pipi_open_sequence(char *, int, int, int);
+__extern pipi_sequence_t *pipi_open_sequence(char const *, int, int, int);
 __extern int pipi_feed_sequence(pipi_sequence_t *, uint8_t *, int, int);
 __extern int pipi_close_sequence(pipi_sequence_t *);
 
diff --git a/pipi/sequence.c b/pipi/sequence.c
index 5969a18..67b8cc9 100644
--- a/pipi/sequence.c
+++ b/pipi/sequence.c
@@ -58,7 +58,8 @@ ffmpeg_codec_t;
 #define PAR_DEN 1
 #define BITRATE (16 * 1024 * 1024)
 
-pipi_sequence_t *pipi_open_sequence(char *file, int width, int height, int fps)
+pipi_sequence_t *pipi_open_sequence(char const *file,
+                                    int width, int height, int fps)
 {
 #if defined USE_FFMPEG
     static int initialised = 0;