diff --git a/src/xfaces.c b/src/xfaces.c
index f7ee19195f..ab624a8d87 100644
--- a/src/xfaces.c
+++ b/src/xfaces.c
@@ -2727,7 +2727,9 @@ merge_face_ref (struct window *w,
 		}
 	      else if (EQ (keyword, QCforeground))
 		{
-		  if (STRINGP (value))
+		  if (NILP (value))
+		    to[LFACE_FOREGROUND_INDEX] = Qunspecified;
+		  else if (STRINGP (value))
 		    to[LFACE_FOREGROUND_INDEX] = value;
 		  else
 		    err = true;