diff --git a/proxy/config.go b/proxy/config.go
index ee86174..182dc84 100644
--- a/proxy/config.go
+++ b/proxy/config.go
@@ -2,6 +2,7 @@ package proxy
 
 import (
 	"fmt"
+	"io"
 	"os"
 	"sort"
 	"strings"
@@ -83,7 +84,16 @@ func (c *Config) FindConfig(modelName string) (ModelConfig, string, bool) {
 }
 
 func LoadConfig(path string) (Config, error) {
-	data, err := os.ReadFile(path)
+	file, err := os.Open(path)
+	if err != nil {
+		return Config{}, err
+	}
+	defer file.Close()
+	return LoadConfigFromReader(file)
+}
+
+func LoadConfigFromReader(r io.Reader) (Config, error) {
+	data, err := io.ReadAll(r)
 	if err != nil {
 		return Config{}, err
 	}
@@ -102,6 +112,9 @@ func LoadConfig(path string) (Config, error) {
 	config.aliases = make(map[string]string)
 	for modelName, modelConfig := range config.Models {
 		for _, alias := range modelConfig.Aliases {
+			if _, found := config.aliases[alias]; found {
+				return Config{}, fmt.Errorf("duplicate alias %s found in model: %s", alias, modelName)
+			}
 			config.aliases[alias] = modelName
 		}
 	}
diff --git a/proxy/config_test.go b/proxy/config_test.go
index 292c87c..bb0ce5a 100644
--- a/proxy/config_test.go
+++ b/proxy/config_test.go
@@ -3,6 +3,7 @@ package proxy
 import (
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -138,14 +139,6 @@ groups:
 }
 
 func TestConfig_GroupMemberIsUnique(t *testing.T) {
-	// Create a temporary YAML file for testing
-	tempDir, err := os.MkdirTemp("", "test-config")
-	if err != nil {
-		t.Fatalf("Failed to create temporary directory: %v", err)
-	}
-	defer os.RemoveAll(tempDir)
-
-	tempFile := filepath.Join(tempDir, "config.yaml")
 	content := `
 models:
   model1:
@@ -171,15 +164,32 @@ groups:
     exclusive: false
     members: ["model2"]
 `
+	// Load the config and verify
+	_, err := LoadConfigFromReader(strings.NewReader(content))
+	assert.Equal(t, "model member model2 is used in multiple groups: group1 and group2", err.Error())
 
-	if err := os.WriteFile(tempFile, []byte(content), 0644); err != nil {
-		t.Fatalf("Failed to write temporary file: %v", err)
-	}
+}
+
+func TestConfig_ModelAliasesAreUnique(t *testing.T) {
+	content := `
+models:
+  model1:
+    cmd: path/to/cmd --arg1 one
+    proxy: "http://localhost:8080"
+    aliases:
+      - m1
+  model2:
+    cmd: path/to/cmd --arg1 one
+    proxy: "http://localhost:8081"
+    checkEndpoint: "/"
+    aliases:
+      - m1
+      - m2
+`
 
 	// Load the config and verify
-	_, err = LoadConfig(tempFile)
-	assert.NotNil(t, err)
-
+	_, err := LoadConfigFromReader(strings.NewReader(content))
+	assert.Equal(t, "duplicate alias m1 found in model: model2", err.Error())
 }
 
 func TestConfig_ModelConfigSanitizedCommand(t *testing.T) {