1 files changed, 1 insertions, 1 deletions
diff --git a/sensor/include/trygvis/sensor/io.h b/sensor/include/trygvis/sensor/io.h
index 71b0b84..304091b 100644
--- a/sensor/include/trygvis/sensor/io.h
+++ b/sensor/include/trygvis/sensor/io.h
@@ -187,7 +187,7 @@ public:
     void write(SampleRecord const &sample) override;
 
 private:
-    vector<SampleKey *> keys;
+    vector<const SampleKey *> keys;
     shared_ptr<ostream> stream;
     const SampleKey *timestamp_key;
 };