diff --git a/prometheus-entrouvert-exporter/prometheus-entrouvert-exporter.py b/prometheus-entrouvert-exporter/prometheus-entrouvert-exporter.py
index 33f8fdd..df9d3cb 100755
--- a/prometheus-entrouvert-exporter/prometheus-entrouvert-exporter.py
+++ b/prometheus-entrouvert-exporter/prometheus-entrouvert-exporter.py
@@ -64,9 +64,9 @@ def etckeeper(ctn):
 
 
 def exim(ctn):
-    with open('/var/log/exim4/mainlog') as fh:
+    with open('/var/log/exim4/mainlog', 'rb') as fh:
         for line in fh.readlines():
-            if " ** " in line:
+            if b" ** " in line:
                 eo_exim.labels(ctn, "errors").inc()
     deferred = int(run("exim -bpc"))
     eo_exim.labels(ctn, "deferred").set(deferred)