diff --git a/include/osmocom/core/signal.h b/include/osmocom/core/signal.h
index 2442e51..097aa19 100644
--- a/include/osmocom/core/signal.h
+++ b/include/osmocom/core/signal.h
@@ -3,13 +3,18 @@
 
 #include <stdint.h>
 
+/*! \defgroup signal Intra-application signals
+ *  @{
+ */
+/*! \file signal.h */
+
 /* subsystem signaling numbers: we split the numberspace for applications and
  * libraries: from 0 to UINT_MAX/2 for applications, from UINT_MAX/2 to
  * UINT_MAX for libraries. */
 #define OSMO_SIGNAL_SS_APPS		0
 #define OSMO_SIGNAL_SS_RESERVED		2147483648
 
-/* signal subsystems. */
+/*! \brief signal subsystems */
 enum {
 	SS_L_GLOBAL		= OSMO_SIGNAL_SS_RESERVED,
 	SS_L_INPUT,
@@ -19,11 +24,12 @@
 #define OSMO_SIGNAL_T_APPS		0
 #define OSMO_SIGNAL_T_RESERVED		2147483648
 
-/* signal types. */
+/*! \brief signal types. */
 enum {
 	S_L_GLOBAL_SHUTDOWN	= OSMO_SIGNAL_T_RESERVED,
 };
 
+/*! signal callback function type */
 typedef int osmo_signal_cbfn(unsigned int subsys, unsigned int signal, void *handler_data, void *signal_data);
 
 
@@ -34,4 +40,6 @@
 /* Dispatch */
 void osmo_signal_dispatch(unsigned int subsys, unsigned int signal, void *signal_data);
 
+/*! }@ */
+
 #endif /* OSMO_SIGNAL_H */