diff --git a/include/osmocom/gsm/cbsp.h b/include/osmocom/gsm/cbsp.h
index 1e705e5..536c54d 100644
--- a/include/osmocom/gsm/cbsp.h
+++ b/include/osmocom/gsm/cbsp.h
@@ -303,7 +303,7 @@
 	} u;
 };
 
-extern const __thread char *osmo_cbsp_errstr;
+extern __thread const char *osmo_cbsp_errstr;
 
 struct msgb *osmo_cbsp_msgb_alloc(void *ctx, const char *name);
 struct msgb *osmo_cbsp_encode(void *ctx, const struct osmo_cbsp_decoded *in);