diff --git a/src/modules/Gmp/my_gmp.h b/src/modules/Gmp/my_gmp.h
index ae43d9fa6c5d008a7901bbcaa6b8e84e1133d172..4c8ba27f6d751c65c5347d6daf29e654af616707 100644
--- a/src/modules/Gmp/my_gmp.h
+++ b/src/modules/Gmp/my_gmp.h
@@ -122,9 +122,7 @@ extern struct program *bignum_program;
 #define OBTOMPQ(o) ((MP_RAT *)(o->storage))
 #define OBTOMPF(o) ((MP_FLT *)(o->storage))
 
-#define IS_MPZ_OBJ(O) ((O)->prog == bignum_program || (O)->prog == mpzmod_program || get_storage((O),mpzmod_program)==(O)->storage)
-#define IS_MPZ_OBJ2(O, INH) ((O->prog) && (((O)->inherits[INH].prog->id & ~1) == PROG_GMP_MPZ_ID))
-
+#define IS_MPZ_OBJ(O) ((O)->prog == bignum_program || (O)->prog == mpzmod_program || ((O)->storage && get_storage((O),mpzmod_program)==(O)->storage))
 #ifndef GMP_NUMB_BITS
 #define GMP_NUMB_BITS (SIZEOF_MP_LIMB_T * CHAR_BIT)
 #endif