diff --git a/doc.go b/doc.go
index f6f764e..9807fea 100644
--- a/doc.go
+++ b/doc.go
@@ -38,6 +38,23 @@ Example:
 		}
 		textSub := slug.Make("water is hot")
 		fmt.Println(textSub) // Will print: "sand-is-hot"
+
+		// as above but goroutine safe, without race hazard
+
+		slugger := slug.New() // captures current global defaults
+
+		enText := slugger.MakeLang("This & that", "en")
+		fmt.Println(enText) // Will print: "this-and-that"
+
+		slugger.Lowercase = false // Keep uppercase characters
+		deUppercaseText := slugger.MakeLang("Diese & Dass", "de")
+		fmt.Println(deUppercaseText) // Will print: "Diese-und-Dass"
+
+		slugger.CustomSub = map[string]string{
+			"water": "sand",
+		}
+		textSub := slugger.Make("water is hot")
+		fmt.Println(textSub) // Will print: "sand-is-hot"
 	}
 
 Requests or bugs?
diff --git a/go.mod b/go.mod
index f528a7a..b13c9a3 100644
--- a/go.mod
+++ b/go.mod
@@ -1,5 +1,5 @@
 module github.com/gosimple/slug
 
-go 1.13
-
 require github.com/rainycape/unidecode v0.0.0-20150907023854-cb7f23ec59be
+
+go 1.13
diff --git a/slug.go b/slug.go
index 272cc3f..8d4f6d6 100644
--- a/slug.go
+++ b/slug.go
@@ -36,6 +36,26 @@ var (
 	regexpMultipleDashes     = regexp.MustCompile("-+")
 )
 
+// Slugger configures slug generation
+type Slugger struct {
+	// CustomSub stores custom substitution map
+	CustomSub map[string]string
+	// CustomRuneSub stores custom rune substitution map
+	CustomRuneSub map[rune]string
+
+	// MaxLength stores maximum slug length.
+	// It's smart so it will cat slug after full word.
+	// By default slugs aren't shortened.
+	// If MaxLength is smaller than length of the first word, then returned
+	// slug will contain only substring from the first word truncated
+	// after MaxLength.
+	MaxLength int
+
+	// Lowercase defines if the resulting slug is transformed to lowercase.
+	// Default is true.
+	Lowercase bool
+}
+
 //=============================================================================
 
 // Make returns slug generated from provided string. Will use "en" as language
@@ -47,12 +67,28 @@ func Make(s string) (slug string) {
 // MakeLang returns slug generated from provided string and will use provided
 // language for chars substitution.
 func MakeLang(s string, lang string) (slug string) {
+	return New().MakeLang(s, lang)
+}
+
+// New returns a Slugger initialized with the current global defaults
+func New() Slugger {
+	return Slugger{
+		CustomSub:     CustomSub,
+		CustomRuneSub: CustomRuneSub,
+		MaxLength:     MaxLength,
+		Lowercase:     Lowercase,
+	}
+}
+
+// MakeLang returns slug generated from provided string and will use provided
+// language for chars substitution.
+func (sl Slugger) MakeLang(s string, lang string) (slug string) {
 	slug = strings.TrimSpace(s)
 
 	// Custom substitutions
 	// Always substitute runes first
-	slug = SubstituteRune(slug, CustomRuneSub)
-	slug = Substitute(slug, CustomSub)
+	slug = SubstituteRune(slug, sl.CustomRuneSub)
+	slug = Substitute(slug, sl.CustomSub)
 
 	// Process string with selected substitution language.
 	// Catch ISO 3166-1, ISO 639-1:2002 and ISO 639-3:2007.
@@ -84,7 +120,7 @@ func MakeLang(s string, lang string) (slug string) {
 	// Process all non ASCII symbols
 	slug = unidecode.Unidecode(slug)
 
-	if Lowercase {
+	if sl.Lowercase {
 		slug = strings.ToLower(slug)
 	}
 
@@ -93,8 +129,8 @@ func MakeLang(s string, lang string) (slug string) {
 	slug = regexpMultipleDashes.ReplaceAllString(slug, "-")
 	slug = strings.Trim(slug, "-_")
 
-	if MaxLength > 0 {
-		slug = smartTruncate(slug)
+	if sl.MaxLength > 0 {
+		slug = smartTruncate(slug, sl.MaxLength)
 	}
 
 	return slug
@@ -131,20 +167,20 @@ func SubstituteRune(s string, sub map[rune]string) string {
 	return buf.String()
 }
 
-func smartTruncate(text string) string {
-	if len(text) < MaxLength {
+func smartTruncate(text string, maxLength int) string {
+	if len(text) < maxLength {
 		return text
 	}
 
 	var truncated string
 	words := strings.SplitAfter(text, "-")
-	// If MaxLength is smaller than length of the first word return word
-	// truncated after MaxLength.
-	if len(words[0]) > MaxLength {
-		return words[0][:MaxLength]
+	// If maxLength is smaller than length of the first word return word
+	// truncated after maxLength.
+	if len(words[0]) > maxLength {
+		return words[0][:maxLength]
 	}
 	for _, word := range words {
-		if len(truncated)+len(word)-1 <= MaxLength {
+		if len(truncated)+len(word)-1 <= maxLength {
 			truncated = truncated + word
 		} else {
 			break
@@ -159,8 +195,17 @@ func smartTruncate(text string) string {
 // It should be in range of the MaxLength var if specified.
 // All output from slug.Make(text) should pass this test.
 func IsSlug(text string) bool {
+	return Slugger{MaxLength: MaxLength}.IsSlug(text)
+}
+
+// IsSlug returns True if provided text does not contain white characters,
+// punctuation, all letters are lower case and only from ASCII range.
+// It could contain `-` and `_` but not at the beginning or end of the text.
+// It should be in range of the MaxLength var if specified.
+// All output from slug.Make(text) should pass this test.
+func (sl Slugger) IsSlug(text string) bool {
 	if text == "" ||
-		(MaxLength > 0 && len(text) > MaxLength) ||
+		(sl.MaxLength > 0 && len(text) > sl.MaxLength) ||
 		text[0] == '-' || text[0] == '_' ||
 		text[len(text)-1] == '-' || text[len(text)-1] == '_' {
 		return false
diff --git a/slug_test.go b/slug_test.go
index e43eeed..10f1101 100644
--- a/slug_test.go
+++ b/slug_test.go
@@ -6,6 +6,7 @@
 package slug
 
 import (
+	"fmt"
 	"testing"
 )
 
@@ -52,12 +53,16 @@ func TestSlugMake(t *testing.T) {
 	}
 
 	for index, st := range testCases {
-		got := Make(st.in)
-		if got != st.want {
-			t.Errorf(
-				"%d. Make(%#v) = %#v; want %#v",
-				index, st.in, got, st.want)
-		}
+		t.Run(fmt.Sprintf("%d", index), func(t *testing.T) {
+			//t.Parallel()
+			st := st
+			got := Make(st.in)
+			if got != st.want {
+				t.Errorf(
+					"%d. Make(%#v) = %#v; want %#v",
+					index, st.in, got, st.want)
+			}
+		})
 	}
 }
 
@@ -116,13 +121,17 @@ func TestSlugMakeLang(t *testing.T) {
 	}
 
 	for index, smlt := range testCases {
-		Lowercase = smlt.lowercase
-		got := MakeLang(smlt.in, smlt.lang)
-		if got != smlt.want {
-			t.Errorf(
-				"%d. MakeLang(%#v, %#v) = %#v; want %#v",
-				index, smlt.in, smlt.lang, got, smlt.want)
-		}
+		t.Run(fmt.Sprintf("%d", index), func(t *testing.T) {
+			//t.Parallel()
+			smlt := smlt // closure
+			Lowercase = smlt.lowercase
+			got := MakeLang(smlt.in, smlt.lang)
+			if got != smlt.want {
+				t.Errorf(
+					"%d. MakeLang(%#v, %#v) = %#v; want %#v",
+					index, smlt.in, smlt.lang, got, smlt.want)
+			}
+		})
 	}
 }
 
@@ -144,14 +153,18 @@ func TestSlugMakeUserSubstituteLang(t *testing.T) {
 	}
 
 	for index, smust := range testCases {
-		CustomSub = smust.cSub
-		got := MakeLang(smust.in, smust.lang)
-		if got != smust.want {
-			t.Errorf(
-				"%d. %#v; MakeLang(%#v, %#v) = %#v; want %#v",
-				index, smust.cSub, smust.in, smust.lang,
-				got, smust.want)
-		}
+		t.Run(fmt.Sprintf("%d", index), func(t *testing.T) {
+			//t.Parallel()
+			smust := smust
+			CustomSub = smust.cSub
+			got := MakeLang(smust.in, smust.lang)
+			if got != smust.want {
+				t.Errorf(
+					"%d. %#v; MakeLang(%#v, %#v) = %#v; want %#v",
+					index, smust.cSub, smust.in, smust.lang,
+					got, smust.want)
+			}
+		})
 	}
 }
 
@@ -170,15 +183,19 @@ func TestSlugMakeSubstituteOrderLang(t *testing.T) {
 	}
 
 	for index, smsot := range testCases {
-		CustomRuneSub = smsot.rSub
-		CustomSub = smsot.sSub
-		got := Make(smsot.in)
-		if got != smsot.want {
-			t.Errorf(
-				"%d. %#v; %#v; Make(%#v) = %#v; want %#v",
-				index, smsot.rSub, smsot.sSub, smsot.in,
-				got, smsot.want)
-		}
+		t.Run(fmt.Sprintf("%d", index), func(t *testing.T) {
+			//t.Parallel()
+			smsot := smsot
+			CustomRuneSub = smsot.rSub
+			CustomSub = smsot.sSub
+			got := Make(smsot.in)
+			if got != smsot.want {
+				t.Errorf(
+					"%d. %#v; %#v; Make(%#v) = %#v; want %#v",
+					index, smsot.rSub, smsot.sSub, smsot.in,
+					got, smsot.want)
+			}
+		})
 	}
 }
 
@@ -195,12 +212,16 @@ func TestSubstituteLang(t *testing.T) {
 	}
 
 	for index, sst := range testCases {
-		got := Substitute(sst.in, sst.cSub)
-		if got != sst.want {
-			t.Errorf(
-				"%d. Substitute(%#v, %#v) = %#v; want %#v",
-				index, sst.in, sst.cSub, got, sst.want)
-		}
+		t.Run(fmt.Sprintf("%d", index), func(t *testing.T) {
+			//t.Parallel()
+			sst := sst
+			got := Substitute(sst.in, sst.cSub)
+			if got != sst.want {
+				t.Errorf(
+					"%d. Substitute(%#v, %#v) = %#v; want %#v",
+					index, sst.in, sst.cSub, got, sst.want)
+			}
+		})
 	}
 }
 
@@ -217,12 +238,16 @@ func TestSubstituteRuneLang(t *testing.T) {
 	}
 
 	for index, ssrt := range testCases {
-		got := SubstituteRune(ssrt.in, ssrt.cSub)
-		if got != ssrt.want {
-			t.Errorf(
-				"%d. SubstituteRune(%#v, %#v) = %#v; want %#v",
-				index, ssrt.in, ssrt.cSub, got, ssrt.want)
-		}
+		t.Run(fmt.Sprintf("%d", index), func(t *testing.T) {
+			//t.Parallel()
+			ssrt := ssrt
+			got := SubstituteRune(ssrt.in, ssrt.cSub)
+			if got != ssrt.want {
+				t.Errorf(
+					"%d. SubstituteRune(%#v, %#v) = %#v; want %#v",
+					index, ssrt.in, ssrt.cSub, got, ssrt.want)
+			}
+		})
 	}
 }
 
@@ -241,13 +266,17 @@ func TestSlugMakeSmartTruncate(t *testing.T) {
 	}
 
 	for index, smstt := range testCases {
-		MaxLength = smstt.maxLength
-		got := Make(smstt.in)
-		if got != smstt.want {
-			t.Errorf(
-				"%d. MaxLength = %v; Make(%#v) = %#v; want %#v",
-				index, smstt.maxLength, smstt.in, got, smstt.want)
-		}
+		t.Run(fmt.Sprintf("%d", index), func(t *testing.T) {
+			//t.Parallel()
+			smstt := smstt
+			MaxLength = smstt.maxLength
+			got := Make(smstt.in)
+			if got != smstt.want {
+				t.Errorf(
+					"%d. MaxLength = %v; Make(%#v) = %#v; want %#v",
+					index, smstt.maxLength, smstt.in, got, smstt.want)
+			}
+		})
 	}
 }
 
@@ -276,8 +305,10 @@ func TestIsSlug(t *testing.T) {
 		{"outside ASCII –", args{"2000–2013"}, false},
 		{"smile ☺", args{"smile ☺"}, false},
 	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
+	for index, tt := range tests {
+		t.Run(fmt.Sprintf("%d", index), func(t *testing.T) {
+			//t.Parallel()
+			tt := tt
 			if got := IsSlug(tt.args.text); got != tt.want {
 				t.Errorf("IsSlug() = %v, want %v", got, tt.want)
 			}
@@ -403,7 +434,7 @@ func BenchmarkSmartTruncateShort(b *testing.B) {
 	b.ReportAllocs()
 	b.ResetTimer()
 	for n := 0; n < b.N; n++ {
-		smartTruncate(shortStr)
+		smartTruncate(shortStr, MaxLength)
 	}
 }
 
@@ -428,7 +459,7 @@ func BenchmarkSmartTruncateLong(b *testing.B) {
 	b.ReportAllocs()
 	b.ResetTimer()
 	for n := 0; n < b.N; n++ {
-		smartTruncate(longStr)
+		smartTruncate(longStr, MaxLength)
 	}
 }