diff --git a/.travis.yml b/.travis.yml
index 5a2b955..6420d1c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,8 @@
 language: go
+env:
+  -  GO111MODULE=on
 sudo: required
 go:
-  - "1.10.x"
   - "1.11.x"
   - tip
 os:
diff --git a/cast_test.go b/cast_test.go
index 1660ed0..d9a1479 100644
--- a/cast_test.go
+++ b/cast_test.go
@@ -872,7 +872,7 @@ func TestToStringMapInt64E(t *testing.T) {
 		{map[string]int32{"v1": int32(33), "v2": int32(88)}, map[string]int64{"v1": 33, "v2": 88}, false},
 		{map[string]uint16{"v1": uint16(33), "v2": uint16(88)}, map[string]int64{"v1": 33, "v2": 88}, false},
 		{map[string]float64{"v1": float64(8.22), "v2": float64(43.32)}, map[string]int64{"v1": 8, "v2": 43}, false},
-			{`{"v1": 67, "v2": 56}`, map[string]int64{"v1": 67, "v2": 56}, false},
+		{`{"v1": 67, "v2": 56}`, map[string]int64{"v1": 67, "v2": 56}, false},
 
 		// errors
 		{nil, nil, true},
diff --git a/caste.go b/caste.go
index 81623c6..a4859fb 100644
--- a/caste.go
+++ b/caste.go
@@ -991,7 +991,7 @@ func ToStringMapE(i interface{}) (map[string]interface{}, error) {
 }
 
 // ToStringMapIntE casts an interface to a map[string]int{} type.
-func ToStringMapIntE(i interface{}) (map[string]int, error)  {
+func ToStringMapIntE(i interface{}) (map[string]int, error) {
 	var m = map[string]int{}
 	if i == nil {
 		return m, fmt.Errorf("unable to cast %#v of type %T to map[string]int", i, i)
@@ -1032,7 +1032,7 @@ func ToStringMapIntE(i interface{}) (map[string]int, error)  {
 }
 
 // ToStringMapInt64E casts an interface to a map[string]int64{} type.
-func ToStringMapInt64E(i interface{}) (map[string]int64, error)  {
+func ToStringMapInt64E(i interface{}) (map[string]int64, error) {
 	var m = map[string]int64{}
 	if i == nil {
 		return m, fmt.Errorf("unable to cast %#v of type %T to map[string]int64", i, i)
@@ -1222,7 +1222,7 @@ func StringToDate(s string) (time.Time, error) {
 		"2006-01-02 15:04:05 -07:00",
 		"2006-01-02 15:04:05 -0700",
 		"2006-01-02 15:04:05Z07:00", // RFC3339 without T
-		"2006-01-02 15:04:05Z0700", // RFC3339 without T or timezone hh:mm colon
+		"2006-01-02 15:04:05Z0700",  // RFC3339 without T or timezone hh:mm colon
 		"2006-01-02 15:04:05",
 		time.Kitchen,
 		time.Stamp,
diff --git a/go.mod b/go.mod
index 6313f39..c1c0232 100644
--- a/go.mod
+++ b/go.mod
@@ -1 +1,7 @@
 module github.com/spf13/cast
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/testify v1.2.2
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..e03ee77
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,6 @@
+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/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 v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=