diff --git a/magnets.c b/magnets.c
index 6a3ac52..2679eb4 100644
--- a/magnets.c
+++ b/magnets.c
@@ -2641,7 +2641,7 @@ int main(int argc, const char *argv[])
     decode_params(p, id);
     err = validate_params(p, true);
     if (err) {
-        fprintf(stderr, "%s: %s", argv[0], err);
+        fprintf(stderr, "%s: %s\n", argv[0], err);
         goto done;
     }