diff --git a/m-core.h b/m-core.h
index 79bec524..43f944f5 100644
--- a/m-core.h
+++ b/m-core.h
@@ -393,6 +393,9 @@
 /* Return the input (delay evaluation) */
 #define M_ID(...)                 __VA_ARGS__
 
+/* Globber the input */
+#define M_EAT(...)
+
 /* M_NARGS: Return number of argument.
    (don't work for empty arg) */
 #define M_NARGS(...)                                                    \
@@ -1044,9 +1047,9 @@ m_core_hash (const void *str, size_t length)
 /* Test if the argument is a valid oplist.
    NOTE: Incomplete test.
 */
-#define M_OPLIST_P(a)                           \
-  M_AND(M_PARENTHESIS_P(a), M_INV(M_PARENTHESIS_P (M_OPFLAT a)))
-
+#define M_OPLIST_P(a)                                                   \
+  M_AND(M_AND(M_PARENTHESIS_P(a), M_INV(M_PARENTHESIS_P (M_OPFLAT a))), \
+        M_EMPTY_P(M_EAT a))
 
 
 /************************************************************/
diff --git a/tests/test-mcore.c b/tests/test-mcore.c
index 90a5c265..fd26bc56 100644
--- a/tests/test-mcore.c
+++ b/tests/test-mcore.c
@@ -233,6 +233,8 @@ static void test_oplist(void)
   assert (!M_OPLIST_P());
   assert (!M_OPLIST_P((())));
   assert (!M_OPLIST_P(INIT(init)));
+  assert (!M_OPLIST_P((INIT(init)) a));
+  assert (!M_OPLIST_P(f(INIT(init)) a));
 
 #define a (INIT(0), CLEAR(clear))
   assert (M_TEST_DISABLED_METHOD_P(INIT, a));