diff --git a/src/post_code.cpp b/src/post_code.cpp
index c62c389..4b14ca1 100644
--- a/src/post_code.cpp
+++ b/src/post_code.cpp
@@ -142,7 +142,7 @@
         cereal::JSONOutputArchive oarchivePostCodes(osPostCodes);
         oarchivePostCodes(postCodes);
     }
-    catch (cereal::Exception& e)
+    catch (const cereal::Exception& e)
     {
         phosphor::logging::log<phosphor::logging::level::ERR>(e.what());
         return "";
@@ -168,7 +168,7 @@
         }
         return false;
     }
-    catch (cereal::Exception& e)
+    catch (const cereal::Exception& e)
     {
         phosphor::logging::log<phosphor::logging::level::ERR>(e.what());
         return false;
@@ -195,7 +195,7 @@
         }
         return false;
     }
-    catch (cereal::Exception& e)
+    catch (const cereal::Exception& e)
     {
         phosphor::logging::log<phosphor::logging::level::ERR>(e.what());
         return false;