diff --git a/src/dec/idec.c b/src/dec/idec.c
index d49ceb0a..672ba10e 100644
--- a/src/dec/idec.c
+++ b/src/dec/idec.c
@@ -538,9 +538,9 @@ VP8StatusCode WebPIUpdate(WebPIDecoder* const idec, const uint8_t* data,
 
 //------------------------------------------------------------------------------
 
-uint8_t* WebPIDecGetRGB(const WebPIDecoder* const idec, int *last_y,
-                        int* width, int* height, int* stride) {
-  if (!idec || !idec->dec_ || idec->params_.mode != MODE_RGB ||
+uint8_t* WebPIDecGetRGB(const WebPIDecoder* const idec, int *last_y, int* width,
+                        int* height, int* stride) {
+  if (!idec || !idec->dec_ || idec->params_.mode == MODE_YUV ||
       idec->state_ <= STATE_PARTS0) {
     return NULL;
   }
diff --git a/src/webp/decode.h b/src/webp/decode.h
index 6c63d54b..60047e37 100644
--- a/src/webp/decode.h
+++ b/src/webp/decode.h
@@ -178,10 +178,11 @@ VP8StatusCode WebPIAppend(WebPIDecoder* const idec, const uint8_t* data,
 VP8StatusCode WebPIUpdate(WebPIDecoder* const idec, const uint8_t* data,
                           uint32_t data_size);
 
-// Returns the RGB image decoded so far. Returns NULL if output params are not
-// initialized yet. *last_y is the index of last decoded row in raster scan
-// order. Some pointers (*last_y, *width etc.) can be NULL if corresponding
-// information is not needed.
+// Returns the r/g/b/(a) image decoded so far. Returns NULL if output params
+// are not initialized yet. The r/g/b/(a) output type corresponds to the mode
+// specified in WebPINew()/WebPINewRGB(). *last_y is the index of last decoded
+// row in raster scan order. Some pointers (*last_y, *width etc.) can be NULL if
+// corresponding information is not needed.
 uint8_t* WebPIDecGetRGB(const WebPIDecoder* const idec, int *last_y,
                         int* width, int* height, int* stride);