diff --git a/lib/roken/write_pid.c b/lib/roken/write_pid.c
index 1be00c344..4ebdcae45 100644
--- a/lib/roken/write_pid.c
+++ b/lib/roken/write_pid.c
@@ -61,7 +61,7 @@ pid_file_write(const char *progname)
 	free(ret);
 	return NULL;
     }
-    fprintf(fp, "%u", (unsigned)getpid());
+    fprintf(fp, "%lu\n", (unsigned long)getpid());
     fclose(fp);
     return ret;
 }