diff --git a/src/gsm/gsm0411_smr.c b/src/gsm/gsm0411_smr.c
index 8003bc8..c6c85e1 100644
--- a/src/gsm/gsm0411_smr.c
+++ b/src/gsm/gsm0411_smr.c
@@ -369,7 +369,7 @@
 }
 
 /* statefull handling for SM-RL SAP messages */
-static struct smrdownstate {
+static const struct smrdownstate {
 	uint32_t	states;
 	int		type;
 	const char 	*name;
@@ -421,7 +421,7 @@
 }
 
 /* statefull handling for MMSMS SAP messages */
-static struct smrdatastate {
+static const struct smrdatastate {
 	uint32_t	states;
 	int		type;
 	const char 	*name;