diff --git a/tests/Makefile b/tests/Makefile
index f691b5f0..e4bba055 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -83,7 +83,7 @@ checkfail: fail-no-oplist
 
 # TODO: should grep failure message?
 fail-no-oplist:
-	for i in 1 2 3 4 5 6 ; do \
+	for i in 1 2 3 4 5 6 7 8 9 ; do \
 	if $(CC) $(CFLAGS) $(CPPFLAGS) -g -c fail-no-oplist.c -o tmp.o -DTEST=$$i 2> fail-no-oplist-$$i.log ; then echo FAILURE: fail-no-oplist-$$i ; false; else echo OK: fail-no-oplist-$$i ; fi \
 	done
 
diff --git a/tests/fail-no-oplist.c b/tests/fail-no-oplist.c
index 278f2d14..cec33d97 100644
--- a/tests/fail-no-oplist.c
+++ b/tests/fail-no-oplist.c
@@ -42,6 +42,34 @@ typedef struct tmp_str_s {
 } tmp_str_t;
 ILIST_DEF(tmpstr, tmp_str_t, DEFAULT_OPLIST)
 
+#elif TEST == 7
+
+#include "m-string.h"
+void f(void)
+{
+  M_LET(x, M_STRING_OPLIST) {
+  }
+}
+
+#elif TEST == 8
+
+#include "m-string.h"
+typedef string_t my_type;
+#define M_OPL_my_type() MSTRING_OPLIST
+void f(void)
+{
+  M_LET(x, my_type) {
+  }
+}
+
+#elif TEST == 9
+
+void f(void)
+{
+  M_LET(x, () ) {
+  }
+}
+
 #else
 # warning TEST variable is out of range.
 #endif