diff --git a/LICENSE b/LICENSE
index 30c1c3e..08cdc7b 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 BSD 3-Clause License
 
-Copyright (c) 2025, Lixen Wraith
+Copyright (c) 2026, Lixen Wraith
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:
diff --git a/config.go b/config.go
index 8e82ffd..73b5e6c 100644
--- a/config.go
+++ b/config.go
@@ -1,4 +1,3 @@
-// FILE: lixenwraith/config/config.go
 // Package config provides thread-safe configuration management for Go applications
 // with support for multiple sources: TOML files, environment variables, command-line
 // arguments, and default values with configurable precedence.
@@ -7,6 +6,7 @@ package config
 import (
 	"fmt"
 	"reflect"
+	"slices"
 	"sync"
 	"sync/atomic"
 )
@@ -50,6 +50,9 @@ type Config struct {
 	version      atomic.Int64
 	structCache  *structCache
 
+	// CLI paths that matched no registered path (reset on each CLI load)
+	unknownCLIKeys []string
+
 	// File watching support
 	watcher        *watcher
 	configFilePath string // Track loaded file path
@@ -249,6 +252,7 @@ func (c *Config) SetSource(source Source, path string, value any) error {
 		c.envData[path] = value
 	case SourceCLI:
 		c.cliData[path] = value
+		c.unknownCLIKeys = nil
 	}
 
 	c.invalidateCache() // Invalidate cache after changes
@@ -337,6 +341,13 @@ func (c *Config) AsStruct() (any, error) {
 	return c.structCache.target, nil
 }
 
+// UnknownCLIKeys returns CLI paths that matched no registered config path
+func (c *Config) UnknownCLIKeys() []string {
+	c.mutex.RLock()
+	defer c.mutex.RUnlock()
+	return slices.Clone(c.unknownCLIKeys)
+}
+
 // computeValue determines the current value based on precedence
 func (c *Config) computeValue(item configItem) any {
 	// Check sources in precedence order
@@ -372,4 +383,4 @@ func (c *Config) populateStruct() error {
 // invalidateCache override Set methods to invalidate cache
 func (c *Config) invalidateCache() {
 	c.version.Add(1)
-}
\ No newline at end of file
+}
diff --git a/go.mod b/go.mod
index d68e9fe..d4aebb9 100644
--- a/go.mod
+++ b/go.mod
@@ -1,10 +1,10 @@
 module github.com/lixenwraith/config
 
-go 1.25.4
+go 1.26.0
 
 require (
-	github.com/BurntSushi/toml v1.5.0
-	github.com/go-viper/mapstructure/v2 v2.4.0
+	github.com/BurntSushi/toml v1.6.0
+	github.com/go-viper/mapstructure/v2 v2.5.0
 	github.com/stretchr/testify v1.10.0
 	gopkg.in/yaml.v3 v3.0.1
 )
diff --git a/go.sum b/go.sum
index ba939f1..e2e2ab4 100644
--- a/go.sum
+++ b/go.sum
@@ -1,9 +1,9 @@
-github.com/BurntSushi/toml v1.5.0 h1:W5quZX/G/csjUnuI8SUYlsHs9M38FC7znL0lIO+DvMg=
-github.com/BurntSushi/toml v1.5.0/go.mod h1:ukJfTF/6rtPPRCnwkur4qwRxa8vTRFBF0uk2lLoLwho=
+github.com/BurntSushi/toml v1.6.0 h1:dRaEfpa2VI55EwlIW72hMRHdWouJeRF7TPYhI+AUQjk=
+github.com/BurntSushi/toml v1.6.0/go.mod h1:ukJfTF/6rtPPRCnwkur4qwRxa8vTRFBF0uk2lLoLwho=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/go-viper/mapstructure/v2 v2.4.0 h1:EBsztssimR/CONLSZZ04E8qAkxNYq4Qp9LvH92wZUgs=
-github.com/go-viper/mapstructure/v2 v2.4.0/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
+github.com/go-viper/mapstructure/v2 v2.5.0 h1:vM5IJoUAy3d7zRSVtIwQgBj7BiWtMPfmPEgAXnvj1Ro=
+github.com/go-viper/mapstructure/v2 v2.5.0/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
diff --git a/loader.go b/loader.go
index 219a1ad..4e1494a 100644
--- a/loader.go
+++ b/loader.go
@@ -435,7 +435,7 @@ func (c *Config) loadEnv(opts LoadOptions) error {
 		transform = defaultEnvTransform(opts.EnvPrefix)
 	}
 
-	// -- 1. Prepare data (Read-Lock to get paths)
+	// 1. Prepare data (Read-Lock to get paths)
 	c.mutex.RLock()
 	paths := make([]string, 0, len(c.items))
 	for p := range c.items {
@@ -443,7 +443,7 @@ func (c *Config) loadEnv(opts LoadOptions) error {
 	}
 	c.mutex.RUnlock()
 
-	// -- 2. Process env vars (No Lock)
+	// 2. Process env vars (No Lock)
 	foundEnvVars := make(map[string]string)
 	for _, path := range paths {
 		if opts.EnvWhitelist != nil && !opts.EnvWhitelist[path] {
@@ -506,6 +506,9 @@ func (c *Config) loadCLI(args []string) error {
 
 	c.cliData = flattenedCLI
 
+	// Reset per load; reloads must not accumulate duplicates
+	c.unknownCLIKeys = c.unknownCLIKeys[:0]
+
 	for path, value := range flattenedCLI {
 		if item, exists := c.items[path]; exists {
 			if item.values == nil {
@@ -514,6 +517,9 @@ func (c *Config) loadCLI(args []string) error {
 			item.values[SourceCLI] = value
 			item.currentValue = c.computeValue(item)
 			c.items[path] = item
+		} else {
+			// Record CLI keys that match no registered path
+			c.unknownCLIKeys = append(c.unknownCLIKeys, path)
 		}
 	}
 
@@ -693,4 +699,4 @@ func detectFormatFromContent(data []byte) string {
 	}
 
 	return ""
-}
\ No newline at end of file
+}