diff --git a/lib/middleware-common/src/call_trace.rs b/lib/middleware-common/src/call_trace.rs
index 04a763abc..6430cc038 100644
--- a/lib/middleware-common/src/call_trace.rs
+++ b/lib/middleware-common/src/call_trace.rs
@@ -2,8 +2,19 @@ use wasmer_runtime_core::{
     codegen::{Event, EventSink, FunctionMiddleware, InternalEvent},
     module::ModuleInfo,
 };
+use std::sync::{Arc, atomic::{Ordering, AtomicU32}};
 
-pub struct CallTrace;
+pub struct CallTrace {
+    counter: Arc<AtomicU32>,
+}
+
+impl CallTrace {
+    pub fn new() -> CallTrace {
+        CallTrace {
+            counter: Arc::new(AtomicU32::new(0)),
+        }
+    }
+}
 
 impl FunctionMiddleware for CallTrace {
     type Error = String;
@@ -13,10 +24,13 @@ impl FunctionMiddleware for CallTrace {
         _module_info: &ModuleInfo,
         sink: &mut EventSink<'a, 'b>,
     ) -> Result<(), Self::Error> {
+        let counter = self.counter.clone();
+
         match op {
             Event::Internal(InternalEvent::FunctionBegin(id)) => sink.push(Event::Internal(
                 InternalEvent::Breakpoint(Box::new(move |_| {
-                    eprintln!("func ({})", id);
+                    let idx = counter.fetch_add(1, Ordering::SeqCst);
+                    eprintln!("[{}] func ({})", idx, id);
                     Ok(())
                 })),
             )),