diff --git a/frame_serialize/CBORStream2Serializer.cpp b/frame_serialize/CBORStream2Serializer.cpp
index 16e8e2c9..c34872f7 100644
--- a/frame_serialize/CBORStream2Serializer.cpp
+++ b/frame_serialize/CBORStream2Serializer.cpp
@@ -232,9 +232,9 @@ inline void CBOR_ENC(CborEncoder &encoder, const char* key, const XrayFluorescen
 inline void CBOR_ENC(CborEncoder &encoder, const Reflection& r) {
     CborEncoder mapEncoder;
     cborErr(cbor_encoder_create_map(&encoder, &mapEncoder, CborIndefiniteLength));
-    CBOR_ENC(mapEncoder, "h", r.h);
-    CBOR_ENC(mapEncoder, "k", r.k);
-    CBOR_ENC(mapEncoder, "l", r.l);
+    CBOR_ENC(mapEncoder, "h", static_cast<int64_t>(r.h));
+    CBOR_ENC(mapEncoder, "k", static_cast<int64_t>(r.k));
+    CBOR_ENC(mapEncoder, "l", static_cast<int64_t>(r.l));
     CBOR_ENC(mapEncoder, "phi", r.delta_phi_deg);
     CBOR_ENC(mapEncoder, "x", r.predicted_x);
     CBOR_ENC(mapEncoder, "y", r.predicted_y);