diff --git a/src/bin/wast.rs b/src/bin/wast.rs
index be74a23f33..08191f51ac 100644
--- a/src/bin/wast.rs
+++ b/src/bin/wast.rs
@@ -168,7 +168,7 @@ fn main() {
         wast_context
             .run_file(Path::new(&filename))
             .unwrap_or_else(|e| {
-                eprintln!("{}", e);
+                eprintln!("{:?}", e);
                 process::exit(1)
             });
     }