diff --git a/heat-config/os-refresh-config/configure.d/55-heat-config b/heat-config/os-refresh-config/configure.d/55-heat-config
index 5baa880..25659c2 100755
--- a/heat-config/os-refresh-config/configure.d/55-heat-config
+++ b/heat-config/os-refresh-config/configure.d/55-heat-config
@@ -187,7 +187,8 @@ def invoke_hook(c, log):
                                stdin=subprocess.PIPE,
                                stdout=subprocess.PIPE,
                                stderr=subprocess.PIPE)
-    stdout, stderr = subproc.communicate(input=json.dumps(signal_data))
+    stdout, stderr = subproc.communicate(
+        input=json.dumps(signal_data).encode('utf-8', 'replace'))
 
     log.info(stdout)