diff --git a/tools/lib/ucalls.py b/tools/lib/ucalls.py
index 4c81200..97d60f2 100755
--- a/tools/lib/ucalls.py
+++ b/tools/lib/ucalls.py
@@ -255,13 +255,15 @@
 def get_data():
     # Will be empty when no language was specified for tracing
     if args.latency:
-        data = list(map(lambda kv: (kv[0].clazz.decode() + "." + \
-                                    kv[0].method.decode(),
+        data = list(map(lambda kv: (kv[0].clazz.decode('utf-8', 'replace') \
+                                    + "." + \
+                                    kv[0].method.decode('utf-8', 'replace'),
                                    (kv[1].num_calls, kv[1].total_ns)),
                    bpf["times"].items()))
     else:
-        data = list(map(lambda kv: (kv[0].clazz.decode() + "." + \
-                                    kv[0].method.decode(),
+        data = list(map(lambda kv: (kv[0].clazz.decode('utf-8', 'replace') \
+                                    + "." + \
+                                    kv[0].method.decode('utf-8', 'replace'),
                                    (kv[1].value, 0)),
                    bpf["counts"].items()))