diff --git a/codegen/templates/D.stg b/codegen/templates/D.stg
index 628fe32..5462628 100644
--- a/codegen/templates/D.stg
+++ b/codegen/templates/D.stg
@@ -889,6 +889,7 @@ package <lexerFile.genPackage>;
 import antlr.v4.runtime.Lexer;
 import antlr.v4.runtime.CharStream;
 import antlr.v4.runtime.InterfaceRuleContext;
+import antlr.v4.runtime.RuleContext;
 import antlr.v4.runtime.RuntimeMetaData;
 import antlr.v4.runtime.Token;
 import antlr.v4.runtime.TokenStream;
diff --git a/source/antlr/v4/runtime/dfa/DFA.d b/source/antlr/v4/runtime/dfa/DFA.d
index b268730..293438f 100644
--- a/source/antlr/v4/runtime/dfa/DFA.d
+++ b/source/antlr/v4/runtime/dfa/DFA.d
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
+ * Copyright (c) 2012-2020 The ANTLR Project. All rights reserved.
  * Use of this file is governed by the BSD 3-clause license that
  * can be found in the LICENSE.txt file in the project root.
  */
@@ -189,14 +189,14 @@ class DFA
         }
 
         DFASerializer serializer = new DFASerializer(this, vocabulary);
-        return serializer.toString();
+        return serializer.toString;
     }
 
     public string toLexerString()
     {
         if (s0  is null) return "";
         DFASerializer serializer = new LexerDFASerializer(this);
-        return serializer.toString();
+        return serializer.toString;
     }
 
 }
diff --git a/source/antlr/v4/runtime/dfa/DFASerializer.d b/source/antlr/v4/runtime/dfa/DFASerializer.d
index d2816b3..5336d10 100644
--- a/source/antlr/v4/runtime/dfa/DFASerializer.d
+++ b/source/antlr/v4/runtime/dfa/DFASerializer.d
@@ -1,31 +1,7 @@
 /*
- * [The "BSD license"]
- *  Copyright (c) 2012 Terence Parr
- *  Copyright (c) 2012 Sam Harwell
- *  All rights reserved.
- *
- *  Redistribution and use in source and binary forms, with or without
- *  modification, are permitted provided that the following conditions
- *  are met:
- *
- *  1. Redistributions of source code must retain the above copyright
- *     notice, this list of conditions and the following disclaimer.
- *  2. Redistributions in binary form must reproduce the above copyright
- *     notice, this list of conditions and the following disclaimer in the
- *     documentation and/or other materials provided with the distribution.
- *  3. The name of the author may not be used to endorse or promote products
- *     derived from this software without specific prior written permission.
- *
- *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
- *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
- *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
- *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * Copyright (c) 2012-2020 The ANTLR Project. All rights reserved.
+ * Use of this file is governed by the BSD 3-clause license that
+ * can be found in the LICENSE.txt file in the project root.
  */
 
 module antlr.v4.runtime.dfa.DFASerializer;
diff --git a/source/antlr/v4/runtime/dfa/LexerDFASerializer.d b/source/antlr/v4/runtime/dfa/LexerDFASerializer.d
index 980aeb4..5308cd1 100644
--- a/source/antlr/v4/runtime/dfa/LexerDFASerializer.d
+++ b/source/antlr/v4/runtime/dfa/LexerDFASerializer.d
@@ -22,7 +22,8 @@ class LexerDFASerializer : DFASerializer
      */
     public override string getEdgeLabel(int i)
     {
-	return "'" ~ to!string(i) ~ "'";
+        import std.format : format;
+        return format!"'%s'"(cast(char)i);
     }
 
 }
diff --git a/test/D.test.stg b/test/D.test.stg
index 2d51dff..8d272e4 100644
--- a/test/D.test.stg
+++ b/test/D.test.stg
@@ -58,7 +58,7 @@ Text() ::= "this.getText.get!(string)"
 
 ValEquals(a,b) ::= <%<a>==<b>%>
 
-TextEquals(a) ::= <%this.getText.get!(string).equals("<a>")%>
+TextEquals(a) ::= <%this.getText.get!(string) == "<a>"%>
 
 PlusText(a) ::= <%"<a>" ~ this.getText.get!(string)%>
 
diff --git a/test/d/BaseDTest.java b/test/d/BaseDTest.java
index 464ad9c..4f83e67 100644
--- a/test/d/BaseDTest.java
+++ b/test/d/BaseDTest.java
@@ -892,11 +892,13 @@ protected void writeParserTestFile(String parserName, String lexerName,
 
     protected void writeLexerTestFile(String lexerName, boolean showDFA) {
         ST outputFileST = new ST(
-            "import std.stdio : File, writefln;\n"
+            "import std.stdio : File, write, writefln;\n"
                 + "\n"
                 + "import antlr.v4.runtime.Token;\n"
                 + "import antlr.v4.runtime.ANTLRInputStream;\n"
                 + "import antlr.v4.runtime.CommonTokenStream;\n"
+                + "import antlr.v4.runtime.Lexer;\n"
+                + "import antlr.v4.runtime.atn.LexerATNSimulator;\n"
                 + "import <lexerName>;\n"
                 + "\n"
                 + "int main(string[] args) {\n"
@@ -907,7 +909,7 @@ protected void writeLexerTestFile(String lexerName, boolean showDFA) {
                 + "  tokens.fill();\n"
                 + "  foreach (token; tokens.getTokens)\n"
                 + "    writefln!\"%s\"(token);\n"
-                + (showDFA ? "  std::cout \\<\\< lexer.getInterpreter\\<atn::LexerATNSimulator>()->getDFA(Lexer::DEFAULT_MODE).toLexerString();\n" : "\n")
+                + (showDFA ? "  write((cast(LexerATNSimulator)lexer.getInterpreter).getDFA(Lexer.DEFAULT_MODE).toLexerString);\n" : "\n")
                 + "  return 0;\n"
                 + "}\n");
         outputFileST.add("lexerName", lexerName);