diff --git a/src/mux/muxi.h b/src/mux/muxi.h
index 0320f811..c1c86d3a 100644
--- a/src/mux/muxi.h
+++ b/src/mux/muxi.h
@@ -174,7 +174,8 @@ uint8_t* ChunkListEmit(const WebPChunk* chunk_list, uint8_t* dst);
 // Initialize.
 void MuxImageInit(WebPMuxImage* const wpi);
 
-// Delete image 'wpi'.
+// Delete image 'wpi' and return the next image in the list or NULL.
+// 'wpi' can be NULL.
 WebPMuxImage* MuxImageDelete(WebPMuxImage* const wpi);
 
 // Delete all images in 'wpi_list'.
diff --git a/src/mux/muxinternal.c b/src/mux/muxinternal.c
index 99e37b26..8795cd17 100644
--- a/src/mux/muxinternal.c
+++ b/src/mux/muxinternal.c
@@ -345,6 +345,7 @@ WebPMuxError MuxImageSetNth(const WebPMuxImage* wpi, WebPMuxImage** wpi_list,
 // MuxImage deletion methods.
 
 WebPMuxImage* MuxImageDelete(WebPMuxImage* const wpi) {
+  // Delete the components of wpi. If wpi is NULL this is a noop.
   WebPMuxImage* const next = MuxImageRelease(wpi);
   free(wpi);
   return next;
diff --git a/src/mux/muxread.c b/src/mux/muxread.c
index 7b8c622e..31b85cb1 100644
--- a/src/mux/muxread.c
+++ b/src/mux/muxread.c
@@ -125,6 +125,7 @@ WebPMux* WebPMuxCreate(const uint8_t* data, uint32_t size, int copy_data,
   size -= RIFF_HEADER_SIZE;
 
   wpi = (WebPMuxImage*)malloc(sizeof(*wpi));
+  if (wpi == NULL) goto Err;
   MuxImageInit(wpi);
 
   // Loop over chunks.