diff --git a/src/vim9compile.c b/src/vim9compile.c
index 6c43ad2..8b58d96 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -2638,6 +2638,11 @@
 	    semsg(_(e_missing_dict_comma), *arg);
 	    goto failret;
 	}
+	if (IS_WHITE_OR_NUL(*whitep))
+	{
+	    semsg(_(e_no_white_before), ",");
+	    return FAIL;
+	}
 	whitep = *arg + 1;
 	*arg = skipwhite(*arg + 1);
     }