diff --git a/quinn-proto/src/tests/mod.rs b/quinn-proto/src/tests/mod.rs
index 0c1da4e7c..4a9b548e9 100644
--- a/quinn-proto/src/tests/mod.rs
+++ b/quinn-proto/src/tests/mod.rs
@@ -1018,7 +1018,7 @@ fn test_flow_control(config: TransportConfig, window_size: usize) {
                 break;
             }
             Err(e) => {
-                panic!(e);
+                panic!("{}", e);
             }
         }
     }
@@ -1049,7 +1049,7 @@ fn test_flow_control(config: TransportConfig, window_size: usize) {
                 break;
             }
             Err(e) => {
-                panic!(e);
+                panic!("{}", e);
             }
         }
     }