diff --git a/pid/builder.cpp b/pid/builder.cpp
index 1fbfbd4..2787bf0 100644
--- a/pid/builder.cpp
+++ b/pid/builder.cpp
@@ -36,7 +36,7 @@
 }
 
 std::unordered_map<int64_t, std::unique_ptr<PIDZone>>
-    buildZones(std::map<int64_t, conf::PIDConf>& zonePids,
+    buildZones(const std::map<int64_t, conf::PIDConf>& zonePids,
                std::map<int64_t, struct conf::ZoneConfig>& zoneConfigs,
                SensorManager& mgr, sdbusplus::bus::bus& modeControlBus)
 {
diff --git a/pid/builder.hpp b/pid/builder.hpp
index e500503..2a83f3f 100644
--- a/pid/builder.hpp
+++ b/pid/builder.hpp
@@ -8,6 +8,6 @@
 #include <unordered_map>
 
 std::unordered_map<int64_t, std::unique_ptr<PIDZone>>
-    buildZones(std::map<int64_t, conf::PIDConf>& zonePids,
+    buildZones(const std::map<int64_t, conf::PIDConf>& zonePids,
                std::map<int64_t, struct conf::ZoneConfig>& zoneConfigs,
                SensorManager& mgr, sdbusplus::bus::bus& modeControlBus);