diff --git a/README.md b/README.md
index 848d92d..64bf474 100644
--- a/README.md
+++ b/README.md
@@ -185,7 +185,7 @@ with ENV:
  * `AutomaticEnv()`
  * `BindEnv(string...) : error`
  * `SetEnvPrefix(string)`
- * `SetEnvReplacer(string...) *strings.Replacer`
+ * `SetEnvKeyReplacer(string...) *strings.Replacer`
 
 _When working with ENV variables, it’s important to recognize that Viper
 treats ENV variables as case sensitive._
@@ -212,7 +212,7 @@ time a `viper.Get` request is made. It will apply the following rules. It will
 check for a environment variable with a name matching the key uppercased and
 prefixed with the `EnvPrefix` if set.
 
-`SetEnvReplacer` allows you to use a `strings.Replacer` object to rewrite Env
+`SetEnvKeyReplacer` allows you to use a `strings.Replacer` object to rewrite Env
 keys to an extent. This is useful if you want to use `-` or something in your
 `Get()` calls, but want your environmental variables to use `_` delimiters. An
 example of using it can be found in `viper_test.go`.
diff --git a/util.go b/util.go
index 3ebada9..c784dad 100644
--- a/util.go
+++ b/util.go
@@ -24,6 +24,7 @@ import (
 	"github.com/hashicorp/hcl"
 	"github.com/magiconair/properties"
 	toml "github.com/pelletier/go-toml"
+	"github.com/spf13/afero"
 	"github.com/spf13/cast"
 	jww "github.com/spf13/jwalterweatherman"
 	"gopkg.in/yaml.v2"
@@ -121,8 +122,8 @@ func absPathify(inPath string) string {
 }
 
 // Check if File / Directory Exists
-func exists(path string) (bool, error) {
-	_, err := v.fs.Stat(path)
+func exists(fs afero.Fs, path string) (bool, error) {
+	_, err := fs.Stat(path)
 	if err == nil {
 		return true, nil
 	}
diff --git a/viper.go b/viper.go
index e87ea89..a7a8ddd 100644
--- a/viper.go
+++ b/viper.go
@@ -789,13 +789,16 @@ func (v *Viper) UnmarshalWithMeta(rawVal interface{}) (mapstructure.Metadata, er
 }
 
 // defaultDecoderConfig returns default mapsstructure.DecoderConfig with support
-// of time.Duration values
+// of time.Duration values & string slices
 func defaultDecoderConfig(output interface{}) *mapstructure.DecoderConfig {
 	return &mapstructure.DecoderConfig{
 		Metadata:         nil,
 		Result:           output,
 		WeaklyTypedInput: true,
-		DecodeHook:       mapstructure.StringToTimeDurationHookFunc(),
+		DecodeHook: mapstructure.ComposeDecodeHookFunc(
+			mapstructure.StringToTimeDurationHookFunc(),
+			mapstructure.StringToSliceHookFunc(","),
+		),
 	}
 }
 
@@ -1576,7 +1579,7 @@ func (v *Viper) searchInPath(in string) (filename string) {
 	jww.DEBUG.Println("Searching for config in ", in)
 	for _, ext := range SupportedExts {
 		jww.DEBUG.Println("Checking for", filepath.Join(in, v.configName+"."+ext))
-		if b, _ := exists(filepath.Join(in, v.configName+"."+ext)); b {
+		if b, _ := exists(v.fs, filepath.Join(in, v.configName+"."+ext)); b {
 			jww.DEBUG.Println("Found: ", filepath.Join(in, v.configName+"."+ext))
 			return filepath.Join(in, v.configName+"."+ext)
 		}
diff --git a/viper_test.go b/viper_test.go
index fdfeea9..cbaae1d 100644
--- a/viper_test.go
+++ b/viper_test.go
@@ -496,7 +496,7 @@ func TestAutoEnvWithPrefix(t *testing.T) {
 	assert.Equal(t, "13", Get("bar"))
 }
 
-func TestSetEnvReplacer(t *testing.T) {
+func TestSetEnvKeyReplacer(t *testing.T) {
 	Reset()
 
 	AutomaticEnv()