diff --git a/tests/util/format.c b/tests/util/format.c
index b3d2abdc..b99cc9c3 100644
--- a/tests/util/format.c
+++ b/tests/util/format.c
@@ -40,10 +40,10 @@
 
 static const struct util_format_info format_info[] = {
 	/* Indexed */
-	{ DRM_FORMAT_C1, "C1" },
-	{ DRM_FORMAT_C2, "C2" },
-	{ DRM_FORMAT_C4, "C4" },
-	{ DRM_FORMAT_C8, "C8" },
+	{ DRM_FORMAT_C1, "C1", .ncolors = 2 },
+	{ DRM_FORMAT_C2, "C2", .ncolors = 4 },
+	{ DRM_FORMAT_C4, "C4", .ncolors = 16 },
+	{ DRM_FORMAT_C8, "C8", .ncolors = 256 },
 	/* YUV packed */
 	{ DRM_FORMAT_UYVY, "UYVY", MAKE_YUV_INFO(YUV_YCbCr | YUV_CY, 2, 2, 2) },
 	{ DRM_FORMAT_VYUY, "VYUY", MAKE_YUV_INFO(YUV_YCrCb | YUV_CY, 2, 2, 2) },
diff --git a/tests/util/format.h b/tests/util/format.h
index 2ce1c021..b847c9f2 100644
--- a/tests/util/format.h
+++ b/tests/util/format.h
@@ -55,6 +55,7 @@ struct util_yuv_info {
 struct util_format_info {
 	uint32_t format;
 	const char *name;
+	unsigned int ncolors;
 	const struct util_rgb_info rgb;
 	const struct util_yuv_info yuv;
 };