diff --git a/src/vnet/interface_api.c b/src/vnet/interface_api.c
index 69bf4b72ba4..65f3a02c86b 100644
--- a/src/vnet/interface_api.c
+++ b/src/vnet/interface_api.c
@@ -1653,6 +1653,7 @@ vl_api_pcap_trace_on_t_handler (vl_api_pcap_trace_on_t *mp)
   unformat_init_cstring (&drop_err_name, (char *) mp->error);
   unformat_user (&drop_err_name, unformat_vlib_error, vlib_get_main (),
 		 &capture_args.drop_err);
+  unformat_free (&drop_err_name);
 
   rv = vnet_pcap_dispatch_trace_configure (&capture_args);
 
@@ -1660,7 +1661,6 @@ vl_api_pcap_trace_on_t_handler (vl_api_pcap_trace_on_t *mp)
 
 out:
   unformat_free (&filename);
-  unformat_free (&drop_err_name);
 
   REPLY_MACRO (VL_API_PCAP_TRACE_ON_REPLY);
 }
diff --git a/test/test_pcap.py b/test/test_pcap.py
index b73a601bcc8..1169dcccfc1 100644
--- a/test/test_pcap.py
+++ b/test/test_pcap.py
@@ -163,6 +163,16 @@ class TestPcap(VppTestCase):
         os.remove("/tmp/trace_any_filter.pcap")
         os.remove("/tmp/trace_drop_err.pcap")
 
+        # Attempting to start a trace with no filename should return an error
+        with self.vapi.assert_negative_api_retval():
+            self.vapi.pcap_trace_on(
+                capture_rx=True,
+                capture_tx=True,
+                filter=True,
+                max_packets=1000,
+                sw_if_index=0,
+            )
+
 
 if __name__ == "__main__":
     unittest.main(testRunner=VppTestRunner)