diff --git a/src/libImaging/Mode.c b/src/libImaging/Mode.c
index 7521f4cda..a9687d6df 100644
--- a/src/libImaging/Mode.c
+++ b/src/libImaging/Mode.c
@@ -179,6 +179,7 @@ const RawModeData RAWMODES[] = {
     [IMAGING_RAWMODE_P_4L] = {"P;4L"},
     [IMAGING_RAWMODE_P_R] = {"P;R"},
     [IMAGING_RAWMODE_R] = {"R"},
+    [IMAGING_RAWMODE_RG] = {"RG"},
     [IMAGING_RAWMODE_RGBAX] = {"RGBAX"},
     [IMAGING_RAWMODE_RGBAXX] = {"RGBAXX"},
     [IMAGING_RAWMODE_RGBA_15] = {"RGBA;15"},