diff --git a/backend_mitsu.h b/backend_mitsu.h
index cba38ed..db647ba 100644
--- a/backend_mitsu.h
+++ b/backend_mitsu.h
@@ -60,7 +60,7 @@ typedef void (*DoColorConvFN)(struct CColorConv3D *this, uint8_t *data, uint16_t
 typedef void (*DoColorConvPlaneFN)(struct CColorConv3D *this, uint8_t *data_r, uint8_t *data_g, uint8_t *data_b, uint32_t planelen);
 typedef struct CPCData *(*get_CPCDataFN)(const char *filename);
 typedef void (*destroy_CPCDataFN)(struct CPCData *data);
-typedef int (*do_image_effectFN)(struct CPCData *cpc, struct CPCData *ecpc, struct BandImage *input, struct BandImage *output, int sharpen, int reverse, uint8_t rew[2]);
+typedef int (*do_image_effectFN)(struct CPCData *cpc, struct CPCData *ecpc, struct BandImage *input, struct BandImage *output, int sharpen, int reverse, uint8_t rew[3]);
 typedef int (*send_image_dataFN)(struct BandImage *out, void *context,
 			       int (*callback_fn)(void *context, void *buffer, uint32_t len));