diff --git a/include/osmocom/gsm/gsm0808.h b/include/osmocom/gsm/gsm0808.h
index 04de46c..38d88ef 100644
--- a/include/osmocom/gsm/gsm0808.h
+++ b/include/osmocom/gsm/gsm0808.h
@@ -41,7 +41,7 @@
 struct msgb *gsm0808_create_dtap(struct msgb *msg, uint8_t link_id);
 void gsm0808_prepend_dtap_header(struct msgb *msg, uint8_t link_id);
 
-const struct tlv_definition *gsm0808_att_tlvdef();
+const struct tlv_definition *gsm0808_att_tlvdef(void);
 
 const char *gsm0808_bssmap_name(uint8_t msg_type);
 const char *gsm0808_bssap_name(uint8_t msg_type);
diff --git a/src/gsm/gsm0808.c b/src/gsm/gsm0808.c
index eae1598..01221bd 100644
--- a/src/gsm/gsm0808.c
+++ b/src/gsm/gsm0808.c
@@ -363,7 +363,7 @@
 	},
 };
 
-const struct tlv_definition *gsm0808_att_tlvdef()
+const struct tlv_definition *gsm0808_att_tlvdef(void)
 {
 	return &bss_att_tlvdef;
 }