diff --git a/util.go b/util.go
index 11150a0..b0903fb 100644
--- a/util.go
+++ b/util.go
@@ -153,7 +153,12 @@ func unmarshallConfigReader(in io.Reader, c map[string]interface{}, configType s
 		}
 		for _, key := range p.Keys() {
 			value, _ := p.Get(key)
-			c[key] = value
+			// recursively build nested maps
+			path := strings.Split(key, ".")
+			lastKey := strings.ToLower(path[len(path)-1])
+			deepestMap := deepSearch(c, path[0:len(path)-1])
+			// set innermost value
+			deepestMap[lastKey] = value
 		}
 	}
 
diff --git a/viper_test.go b/viper_test.go
index 3394dc7..24740b3 100644
--- a/viper_test.go
+++ b/viper_test.go
@@ -8,6 +8,7 @@ package viper
 import (
 	"bytes"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"os"
 	"path"
@@ -104,8 +105,9 @@ var remoteExample = []byte(`{
 
 func initConfigs() {
 	Reset()
+	var r io.Reader
 	SetConfigType("yaml")
-	r := bytes.NewReader(yamlExample)
+	r = bytes.NewReader(yamlExample)
 	unmarshalReader(r, v.config)
 
 	SetConfigType("json")
@@ -420,9 +422,9 @@ func TestSetEnvReplacer(t *testing.T) {
 func TestAllKeys(t *testing.T) {
 	initConfigs()
 
-	ks := sort.StringSlice{"title", "newkey", "owner", "name", "beard", "ppu", "batters", "hobbies", "clothing", "age", "hacker", "id", "type", "eyes", "p_id", "p_ppu", "p_batters.batter.type", "p_type", "p_name", "foos"}
+	ks := sort.StringSlice{"title", "newkey", "owner", "name", "beard", "ppu", "batters", "hobbies", "clothing", "age", "hacker", "id", "type", "eyes", "p_id", "p_ppu", "p_batters", "p_type", "p_name", "foos"}
 	dob, _ := time.Parse(time.RFC3339, "1979-05-27T07:32:00Z")
-	all := map[string]interface{}{"owner": map[string]interface{}{"organization": "MongoDB", "Bio": "MongoDB Chief Developer Advocate & Hacker at Large", "dob": dob}, "title": "TOML Example", "ppu": 0.55, "eyes": "brown", "clothing": map[interface{}]interface{}{"trousers": "denim", "jacket": "leather", "pants": map[interface{}]interface{}{"size": "large"}}, "id": "0001", "batters": map[string]interface{}{"batter": []interface{}{map[string]interface{}{"type": "Regular"}, map[string]interface{}{"type": "Chocolate"}, map[string]interface{}{"type": "Blueberry"}, map[string]interface{}{"type": "Devil's Food"}}}, "hacker": true, "beard": true, "hobbies": []interface{}{"skateboarding", "snowboarding", "go"}, "age": 35, "type": "donut", "newkey": "remote", "name": "Cake", "p_id": "0001", "p_ppu": "0.55", "p_name": "Cake", "p_batters.batter.type": "Regular", "p_type": "donut", "foos": []map[string]interface{}{map[string]interface{}{"foo": []map[string]interface{}{map[string]interface{}{"key": 1}, map[string]interface{}{"key": 2}, map[string]interface{}{"key": 3}, map[string]interface{}{"key": 4}}}}}
+	all := map[string]interface{}{"owner": map[string]interface{}{"organization": "MongoDB", "Bio": "MongoDB Chief Developer Advocate & Hacker at Large", "dob": dob}, "title": "TOML Example", "ppu": 0.55, "eyes": "brown", "clothing": map[string]interface{}{"trousers": "denim", "jacket": "leather", "pants": map[string]interface{}{"size": "large"}}, "id": "0001", "batters": map[string]interface{}{"batter": []interface{}{map[string]interface{}{"type": "Regular"}, map[string]interface{}{"type": "Chocolate"}, map[string]interface{}{"type": "Blueberry"}, map[string]interface{}{"type": "Devil's Food"}}}, "hacker": true, "beard": true, "hobbies": []interface{}{"skateboarding", "snowboarding", "go"}, "age": 35, "type": "donut", "newkey": "remote", "name": "Cake", "p_id": "0001", "p_ppu": "0.55", "p_name": "Cake", "p_batters": map[string]interface{}{"batter": map[string]interface{}{"type": "Regular"}}, "p_type": "donut", "foos": []map[string]interface{}{map[string]interface{}{"foo": []map[string]interface{}{map[string]interface{}{"key": 1}, map[string]interface{}{"key": 2}, map[string]interface{}{"key": 3}, map[string]interface{}{"key": 4}}}}}
 
 	var allkeys sort.StringSlice
 	allkeys = AllKeys()