diff --git a/apps/shared/y4m.c b/apps/shared/y4m.c
index 695561e..8c80772 100644
--- a/apps/shared/y4m.c
+++ b/apps/shared/y4m.c
@@ -215,9 +215,10 @@
     struct y4mFrameIterator frame;
     frame.width = -1;
     frame.height = -1;
-    frame.depth = -1;
+    // Default to the color space "C420" to match the defaults of aomenc and ffmpeg.
+    frame.depth = 8;
     frame.hasAlpha = AVIF_FALSE;
-    frame.format = AVIF_PIXEL_FORMAT_NONE;
+    frame.format = AVIF_PIXEL_FORMAT_YUV420;
     frame.range = AVIF_RANGE_LIMITED;
     frame.chromaSamplePosition = AVIF_CHROMA_SAMPLE_POSITION_UNKNOWN;
     memset(&frame.sourceTiming, 0, sizeof(avifAppSourceTiming));
@@ -338,8 +339,7 @@
         goto cleanup;
     }
 
-    if ((frame.width < 1) || (frame.height < 1) || ((frame.depth != 8) && (frame.depth != 10) && (frame.depth != 12)) ||
-        (frame.format == AVIF_PIXEL_FORMAT_NONE)) {
+    if ((frame.width < 1) || (frame.height < 1) || ((frame.depth != 8) && (frame.depth != 10) && (frame.depth != 12))) {
         fprintf(stderr, "Failed to parse y4m header (not enough information): %s\n", frame.displayFilename);
         goto cleanup;
     }