diff --git a/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_support.c b/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_support.c
index 2e51ba8674..4e59b6ae33 100644
--- a/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_support.c
+++ b/libs/freetdm/src/ftmod/ftmod_sangoma_ss7/ftmod_sangoma_ss7_support.c
@@ -213,7 +213,7 @@ ftdm_status_t copy_cdPtyNum_from_sngss7(ftdm_channel_t *ftdmchan, SiCdPtyNum *cd
 
 ftdm_status_t copy_cdPtyNum_to_sngss7(ftdm_channel_t *ftdmchan, SiCdPtyNum *cdPtyNum)
 {
-	char	*val = NULL;
+	const char	*val = NULL;
 	ftdm_caller_data_t *caller_data = &ftdmchan->caller_data;
 	sngss7_chan_data_t	*sngss7_info = ftdmchan->call_data;