diff --git a/TODO-RELEASE b/TODO-RELEASE
index 436d417cb..6ac8db895 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -7,4 +7,5 @@
 # If any interfaces have been added since the last public release: c:r:a + 1.
 # If any interfaces have been removed or changed since the last public release: c:r:0.
 #library	what			description / commit summary line
-libosmocore new API osmo_sockaddr_is_any()
\ No newline at end of file
+libosmocore new API osmo_sockaddr_is_any()
+libosmocore	ABI breakage		OSMO_NUM_DLIB change affecting internal_cat[]
diff --git a/include/osmocom/core/logging.h b/include/osmocom/core/logging.h
index f1304f59d..5ae38c750 100644
--- a/include/osmocom/core/logging.h
+++ b/include/osmocom/core/logging.h
@@ -152,7 +152,9 @@ void logp(int subsys, const char *file, int line, int cont, const char *format,
 #define DLIUUP		-24	/*!< Osmocom IuUP layer */
 #define DLPFCP		-25	/*!< Osmocom Packet Forwarding Control Protocol */
 #define DLCSN1		-26	/*!< CSN.1 (Concrete Syntax Notation 1) codec */
-#define OSMO_NUM_DLIB	26	/*!< Number of logging sub-systems in libraries */
+#define DLM2PA		-27	/*!< Osmocom M2PA (libosmo-sigtran) */
+#define DLM2UA		-28	/*!< Reserved for future Osmocom M2UA (libosmo-sigtran) */
+#define OSMO_NUM_DLIB	28	/*!< Number of logging sub-systems in libraries */
 
 /* Colors that can be used in log_info_cat.color */
 #define OSMO_LOGCOLOR_NORMAL NULL