diff --git a/go.mod b/go.mod
index 99c48a5ef8..33449f4ca0 100644
--- a/go.mod
+++ b/go.mod
@@ -2,6 +2,8 @@ module github.com/tdewolff/minify/v2
 
 go 1.13
 
+replace github.com/tdewolff/parse/v2 => ../parse
+
 require (
 	github.com/cheekybits/is v0.0.0-20150225183255-68e9c0620927 // indirect
 	github.com/dustin/go-humanize v1.0.0
diff --git a/js/js.go b/js/js.go
index 03ce83e365..3a1dcaf13f 100644
--- a/js/js.go
+++ b/js/js.go
@@ -388,6 +388,9 @@ func (m *jsMinifier) minifyStmt(i js.IStmt) {
 			}
 			m.requireSemicolon()
 		}
+	case *js.DirectivePrologueStmt:
+		m.write(stmt.Value)
+		m.requireSemicolon()
 	}
 }
 
diff --git a/js/js_test.go b/js/js_test.go
index 0c77265f7f..ec641771d8 100644
--- a/js/js_test.go
+++ b/js/js_test.go
@@ -126,29 +126,29 @@ func TestJS(t *testing.T) {
 		{`try {a} finally {c}`, `try{a}finally{c}`},
 		{`a=b;c=d`, `a=b,c=d`},
 
-		// strings
-		{`""`, `""`},
-		{`"\x7"`, `"\x7"`},
-		{`"string\'string"`, `"string'string"`},
-		{`'string\"string'`, `'string"string'`},
-		{`'string\t\f\v\bstring'`, "'string\t\f\v\bstring'"},
-		{`"string\a\c\'string"`, `"stringac'string"`},
-		{`"string\∀string"`, `"string∀string"`},
-		{`"string\0\uFFFFstring"`, `"string\0\uFFFFstring"`},
-		{`"string\x00\x55\x0A\x0D\x22\x27string"`, `"string\0U\n\r\"'string"`},
-		{`"string\000\12\015\042\47\411string"`, `"string\0\n\r\"'!1string"`},
-		{"'string\\n\\rstring'", "'string\\n\\rstring'"},
-		{"'string\\\r\nstring\\\nstring\\\rstring\\\u2028string\\\u2029string'", "'stringstringstringstringstringstring'"},
-		{`"str1ng" + "str2ng"`, `"str1ngstr2ng"`},
-		{`"str1ng" + "str2ng" + "str3ng"`, `"str1ngstr2ngstr3ng"`},
-		{`"padding" + this`, `"padding"+this`},
-		{`"<\/script>"`, `"<\/script>"`},
-		{`"</scr"+"ipt>"`, `"<\/script>"`},
-		{`"\""`, `'"'`},
-		{`'\'""'`, `'\'""'`},
-		{`"\"\"a'"`, `'""a\''`},
-		{`"'" + '"'`, `"'\""`},
-		{`'"' + "'"`, `'"\''`},
+		// strings (prepend '0,' to avoid being a directive prologue)
+		{`0,""`, `0,""`},
+		{`0,"\x7"`, `0,"\x7"`},
+		{`0,"string\'string"`, `0,"string'string"`},
+		{`0,'string\"string'`, `0,'string"string'`},
+		{`0,'string\t\f\v\bstring'`, "0,'string\t\f\v\bstring'"},
+		{`0,"string\a\c\'string"`, `0,"stringac'string"`},
+		{`0,"string\∀string"`, `0,"string∀string"`},
+		{`0,"string\0\uFFFFstring"`, `0,"string\0\uFFFFstring"`},
+		{`0,"string\x00\x55\x0A\x0D\x22\x27string"`, `0,"string\0U\n\r\"'string"`},
+		{`0,"string\000\12\015\042\47\411string"`, `0,"string\0\n\r\"'!1string"`},
+		{"0,'string\\n\\rstring'", "0,'string\\n\\rstring'"},
+		{"0,'string\\\r\nstring\\\nstring\\\rstring\\\u2028string\\\u2029string'", "0,'stringstringstringstringstringstring'"},
+		{`0,"str1ng" + "str2ng"`, `0,"str1ngstr2ng"`},
+		{`0,"str1ng" + "str2ng" + "str3ng"`, `0,"str1ngstr2ngstr3ng"`},
+		{`0,"padding" + this`, `0,"padding"+this`},
+		{`0,"<\/script>"`, `0,"<\/script>"`},
+		{`0,"</scr"+"ipt>"`, `0,"<\/script>"`},
+		{`0,"\""`, `0,'"'`},
+		{`0,'\'""'`, `0,'\'""'`},
+		{`0,"\"\"a'"`, `0,'""a\''`},
+		{`0,"'" + '"'`, `0,"'\""`},
+		{`0,'"' + "'"`, `0,'"\''`},
 
 		// rename true, false, undefined, Infinity
 		{`x=true`, `x=!0`},
@@ -312,6 +312,7 @@ func TestJS(t *testing.T) {
 		{`var a;var {}=b;`, `var a;{}=b`},
 		{`"use strict";var a;var b;b=5`, `"use strict";var b=5,a`},
 		{`"use strict";z+=6;var a;var b;b=5`, `"use strict";var a,b;z+=6,b=5`},
+		{`!function(){"use strict";return a}`, `!function(){"use strict";return a}`},
 
 		// function and method declarations
 		{`function g(){return}`, `function g(){}`},
diff --git a/js/vars.go b/js/vars.go
index efa4164ce1..24db40bb6e 100644
--- a/js/vars.go
+++ b/js/vars.go
@@ -200,9 +200,11 @@ func (m *jsMinifier) hoistVars(body *js.BlockStmt) *js.VarDecl {
 
 		// ignore "use strict"
 		declStart := 0
-		if expr, ok := body.List[0].(*js.ExprStmt); ok {
-			if lit, ok := expr.Value.(*js.LiteralExpr); ok && lit.TokenType == js.StringToken && bytes.Equal(lit.Data, useStrictBytes) {
-				declStart = 1
+		for {
+			if _, ok := body.List[declStart].(*js.DirectivePrologueStmt); ok {
+				declStart++
+			} else {
+				break
 			}
 		}