diff --git a/include/cln/config.h.in b/include/cln/config.h.in
index 42cfbaf..f1c7c3d 100644
--- a/include/cln/config.h.in
+++ b/include/cln/config.h.in
@@ -10,5 +10,17 @@
 /* compiler supports the `long long' type */
 #undef HAVE_LONGLONG
 
+/* 
+ * Numbers in the heap are stored as "digit" (or "limb" in GMP speak)
+ * sequences. A digit is an unsigned int with sizeof(void *)*CHAR_BIT bits.
+ * It should be 8 or 16 or 32 or 64 bits. If CLN is sitting on top of GMP
+ * it should match mp_limb_t
+ */
+#undef GMP_DEMANDS_UINTD_INT
+
+#undef GMP_DEMANDS_UINTD_LONG
+
+#undef GMP_DEMANDS_UINTD_LONG_LONG
+
 #endif /* _CL_CONFIG_PUBLIC_H */