diff --git a/phosphor-regulators/src/id_map.cpp b/phosphor-regulators/src/id_map.cpp
index d39fa4f..0f7d3ac 100644
--- a/phosphor-regulators/src/id_map.cpp
+++ b/phosphor-regulators/src/id_map.cpp
@@ -25,17 +25,35 @@
 
 void IDMap::addDevice(Device& device)
 {
-    deviceMap[device.getID()] = &device;
+    const std::string& id = device.getID();
+    if (deviceMap.count(id) != 0)
+    {
+        throw std::invalid_argument{"Unable to add device: Duplicate ID \"" +
+                                    id + '"'};
+    }
+    deviceMap[id] = &device;
 }
 
 void IDMap::addRail(Rail& rail)
 {
-    railMap[rail.getID()] = &rail;
+    const std::string& id = rail.getID();
+    if (railMap.count(id) != 0)
+    {
+        throw std::invalid_argument{"Unable to add rail: Duplicate ID \"" + id +
+                                    '"'};
+    }
+    railMap[id] = &rail;
 }
 
 void IDMap::addRule(Rule& rule)
 {
-    ruleMap[rule.getID()] = &rule;
+    const std::string& id = rule.getID();
+    if (ruleMap.count(id) != 0)
+    {
+        throw std::invalid_argument{"Unable to add rule: Duplicate ID \"" + id +
+                                    '"'};
+    }
+    ruleMap[id] = &rule;
 }
 
 } // namespace phosphor::power::regulators
diff --git a/phosphor-regulators/src/id_map.hpp b/phosphor-regulators/src/id_map.hpp
index 289c7a9..c466f23 100644
--- a/phosphor-regulators/src/id_map.hpp
+++ b/phosphor-regulators/src/id_map.hpp
@@ -47,6 +47,8 @@
     /**
      * Adds the specified device to this IDMap.
      *
+     * Throws invalid_argument if the device's ID already exists in the map.
+     *
      * @param device device to add
      */
     void addDevice(Device& device);
@@ -54,6 +56,8 @@
     /**
      * Adds the specified rail to this IDMap.
      *
+     * Throws invalid_argument if the rail's ID already exists in the map.
+     *
      * @param rail rail to add
      */
     void addRail(Rail& rail);
@@ -61,6 +65,8 @@
     /**
      * Adds the specified rule to this IDMap.
      *
+     * Throws invalid_argument if the rule's ID already exists in the map.
+     *
      * @param rule rule to add
      */
     void addRule(Rule& rule);
diff --git a/phosphor-regulators/test/id_map_tests.cpp b/phosphor-regulators/test/id_map_tests.cpp
index d3053d7..991949b 100644
--- a/phosphor-regulators/test/id_map_tests.cpp
+++ b/phosphor-regulators/test/id_map_tests.cpp
@@ -62,6 +62,21 @@
 
     // Verify different device is not in map
     EXPECT_THROW(idMap.getDevice("vio_reg2"), std::invalid_argument);
+
+    // Test where device ID already exists in map
+    try
+    {
+        i2cInterface =
+            i2c::create(1, 0x72, i2c::I2CInterface::InitialState::CLOSED);
+        Device device2{"vio_reg", true, "/system/chassis/motherboard/vio_reg2",
+                       std::move(i2cInterface)};
+        idMap.addDevice(device2);
+    }
+    catch (const std::invalid_argument& error)
+    {
+        EXPECT_STREQ(error.what(),
+                     "Unable to add device: Duplicate ID \"vio_reg\"");
+    }
 }
 
 TEST(IDMapTests, AddRail)
@@ -92,6 +107,17 @@
 
     // Verify different rail is not in map
     EXPECT_THROW(idMap.getRail("vcs0"), std::invalid_argument);
+
+    // Test where rail ID already exists in map
+    try
+    {
+        Rail rail2{"vio0"};
+        idMap.addRail(rail2);
+    }
+    catch (const std::invalid_argument& error)
+    {
+        EXPECT_STREQ(error.what(), "Unable to add rail: Duplicate ID \"vio0\"");
+    }
 }
 
 TEST(IDMapTests, AddRule)
@@ -123,6 +149,18 @@
     // Verify different rule is not in map
     EXPECT_THROW(idMap.getRule("set_voltage_rule_page0"),
                  std::invalid_argument);
+
+    // Test where rule ID already exists in map
+    try
+    {
+        Rule rule2{"set_voltage_rule", std::vector<std::unique_ptr<Action>>{}};
+        idMap.addRule(rule2);
+    }
+    catch (const std::invalid_argument& error)
+    {
+        EXPECT_STREQ(error.what(),
+                     "Unable to add rule: Duplicate ID \"set_voltage_rule\"");
+    }
 }
 
 TEST(IDMapTests, GetDevice)