diff --git a/src/vim9compile.c b/src/vim9compile.c
index d9908d3..cd5e45b 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -2996,6 +2996,11 @@
 	    return FAIL;
 	}
 	whitep = *arg + 1;
+	if (!IS_WHITE_OR_NUL(*whitep))
+	{
+	    semsg(_(e_white_space_required_after_str), ",");
+	    return FAIL;
+	}
 	*arg = skipwhite(*arg + 1);
     }