diff --git a/src/input/misdn.c b/src/input/misdn.c
index f72b496..9315e23 100644
--- a/src/input/misdn.c
+++ b/src/input/misdn.c
@@ -691,7 +691,7 @@
 		ret = osmo_fd_register(bfd);
 		if (ret < 0) {
 			fprintf(stderr, "could not register FD: %s\n",
-				strerror(ret));
+				strerror(-ret));
 			return ret;
 		}
 	}