diff --git a/radar-jersey/src/main/kotlin/org/radarbase/jersey/config/ConfigLoader.kt b/radar-jersey/src/main/kotlin/org/radarbase/jersey/config/ConfigLoader.kt
index 3ed3080..8db16c3 100644
--- a/radar-jersey/src/main/kotlin/org/radarbase/jersey/config/ConfigLoader.kt
+++ b/radar-jersey/src/main/kotlin/org/radarbase/jersey/config/ConfigLoader.kt
@@ -31,9 +31,8 @@ object ConfigLoader {
         factoryClass: Class<out EnhancerFactory>,
         vararg parameters: Any,
     ): ResourceConfig {
-        val enhancerFactory = factoryClass
-            .getConstructor(*parameters.map { it.javaClass }.toTypedArray())
-            .newInstance(*parameters)
+        val enhancerFactory =
+            factoryClass.getConstructor(*parameters.map { it.javaClass }.toTypedArray()).newInstance(*parameters)
         return createResourceConfig(enhancerFactory.createEnhancers())
     }
 
@@ -57,8 +56,7 @@ object ConfigLoader {
             exitProcess(0)
         }
 
-        val configFile = args.firstOrNull()?.let { Path(it) }
-            ?: fileNames.map { Path(it) }.firstOrNull { it.exists() }
+        val configFile = args.firstOrNull()?.let { Path(it) } ?: fileNames.map { Path(it) }.firstOrNull { it.exists() }
         requireNotNull(configFile) { "Configuration not provided." }
 
         logger.info("Reading configuration from {}", configFile.toAbsolutePath())
@@ -113,22 +111,21 @@ object ConfigLoader {
      * Create a resourceConfig based on the provided resource enhancers. This method also disables
      * the WADL since it may be identified as a security risk.
      */
-    fun createResourceConfig(enhancers: List<JerseyResourceEnhancer>): ResourceConfig =
-        ResourceConfig().apply {
-            property("jersey.config.server.wadl.disableWadl", true)
-            enhancers.forEach { enhancer ->
-                packages(*enhancer.packages)
-                registerClasses(*enhancer.classes)
-                enhancer.enhanceResources(this@apply)
-            }
-
-            register(object : AbstractBinder() {
-                override fun configure() {
-                    enhancers.forEach { it.enhanceBinder(this) }
-                }
-            })
+    fun createResourceConfig(enhancers: List<JerseyResourceEnhancer>): ResourceConfig = ResourceConfig().apply {
+        property("jersey.config.server.wadl.disableWadl", true)
+        enhancers.forEach { enhancer ->
+            packages(*enhancer.packages)
+            registerClasses(*enhancer.classes)
+            enhancer.enhanceResources(this@apply)
         }
 
+        register(object : AbstractBinder() {
+            override fun configure() {
+                enhancers.forEach { it.enhanceBinder(this) }
+            }
+        })
+    }
+
     val logger: Logger = LoggerFactory.getLogger(ConfigLoader::class.java)
 
     /**
@@ -137,12 +134,16 @@ object ConfigLoader {
      */
     inline fun <T> T.copyEnv(
         key: String,
-        doCopy: T.(String?) -> T,
-    ): T = copyOnChange<T, String?>(
-        original = null,
-        modification = { System.getenv(key) },
-        doCopy = doCopy,
-    )
+        envVarAccessor: (String?) -> String? = System::getenv,
+        doCopy: T.(String) -> T,
+    ): T {
+        val newValue = envVarAccessor(key)
+        return if (newValue != null) {
+            doCopy(newValue)
+        } else {
+            this
+        }
+    }
 
     /**
      * Perform copy if the [modification] function makes any change to an [original] value.
diff --git a/radar-jersey/src/test/kotlin/org/radarbase/jersey/config/ConfigLoaderTest.kt b/radar-jersey/src/test/kotlin/org/radarbase/jersey/config/ConfigLoaderTest.kt
index 7fd52f6..7f892e1 100644
--- a/radar-jersey/src/test/kotlin/org/radarbase/jersey/config/ConfigLoaderTest.kt
+++ b/radar-jersey/src/test/kotlin/org/radarbase/jersey/config/ConfigLoaderTest.kt
@@ -2,14 +2,44 @@ package org.radarbase.jersey.config
 
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Test
+import org.radarbase.jersey.config.ConfigLoader.copyEnv
 
 internal class ConfigLoaderTest {
+
+    val testFile = javaClass.getResource("/config/test.yaml")?.file.toString()
+    val config = ConfigLoader.loadConfig<Config>(testFile, emptyArray())
+
     @Test
     fun loadConfig() {
-        val testFile = javaClass.getResource("/config/test.yaml")?.file.toString()
-        val config = ConfigLoader.loadConfig<Config>(testFile, emptyArray())
-        assertEquals(Config(mapOf("test" to "a")), config)
+        assertEquals(
+            NestedConfig(requiredArg = "a", optionalArg = "b"),
+            config.config,
+        )
+    }
+
+    @Test
+    fun testEnvOverride() {
+        assertEquals(
+            NestedConfig(requiredArg = "overridden_required_arg", optionalArg = "overridden_optional_arg"),
+            config.config.withEnv(),
+        )
+    }
+
+    data class NestedConfig(
+        val requiredArg: String,
+        val optionalArg: String?,
+    ) {
+        val envVarsMock = mapOf(
+            Pair("OPTIONAL_ARG", "overridden_optional_arg"),
+            Pair("REQUIRED_ARG", "overridden_required_arg"),
+        )
+
+        fun withEnv(): NestedConfig = this
+            .copyEnv("OPTIONAL_ARG", { envVarsMock[it] }) { copy(optionalArg = it) }
+            .copyEnv("REQUIRED_ARG", { envVarsMock[it] }) { copy(requiredArg = it) }
     }
 
-    data class Config(val config: Map<String, String>)
+    data class Config(
+        val config: NestedConfig,
+    )
 }
diff --git a/radar-jersey/src/test/resources/config/test.yaml b/radar-jersey/src/test/resources/config/test.yaml
index 36257ca..03b2646 100644
--- a/radar-jersey/src/test/resources/config/test.yaml
+++ b/radar-jersey/src/test/resources/config/test.yaml
@@ -1,2 +1,3 @@
 config:
-  test: a
+  requiredArg: a
+  optionalArg: b