diff --git a/pom.xml b/pom.xml
index a56fcb5..fe718e6 100644
--- a/pom.xml
+++ b/pom.xml
@@ -57,6 +57,10 @@
                   </goals>
                </execution>
             </executions>
+            <configuration>
+               <symbolsName>SymbolConstants</symbolsName>
+               <symbolsInterface>true</symbolsInterface>
+            </configuration>
          </plugin>
 
          <plugin>
diff --git a/src/main/java/main/Driver.java b/src/main/java/main/Driver.java
index 736d66e..cb04c40 100644
--- a/src/main/java/main/Driver.java
+++ b/src/main/java/main/Driver.java
@@ -12,7 +12,7 @@
 import com.beust.jcommander.ParameterException;
 import java_cup.runtime.Symbol;
 import parse.Lexer;
-import parse.sym;
+import parse.SymbolConstants;
 
 // command line options
 class DriverOptions {
@@ -84,7 +84,7 @@ public static void lexicalAnalysis(Reader input) throws IOException {
       do {
          tok = lexer.next_token();
          System.out.println(tok);
-      } while (tok.sym != sym.EOF);
+      } while (tok.sym != SymbolConstants.EOF);
    }
 
 }
diff --git a/src/main/jflex/lexer.jflex b/src/main/jflex/lexer.jflex
index 613f1d5..36a9147 100644
--- a/src/main/jflex/lexer.jflex
+++ b/src/main/jflex/lexer.jflex
@@ -7,19 +7,21 @@ import java_cup.runtime.Symbol;
 %public
 %final
 %class Lexer
+%implements SymbolConstants
+%cupsym SymbolConstants
 %cup
 
 %%
 
 [ \t\f\n\r]+         { /* skip */ }
 
-[0-9]+ ("." [0-9]+)? { return new Symbol(sym.LITINT, yytext()); }
+[0-9]+ ("." [0-9]+)? { return new Symbol(LITINT, yytext()); }
 
-"+"                  { return new Symbol(sym.PLUS); }
-"-"                  { return new Symbol(sym.MINUS); }
-"*"                  { return new Symbol(sym.TIMES); }
-"/"                  { return new Symbol(sym.DIV); }
-"("                  { return new Symbol(sym.LPAREN); }
-")"                  { return new Symbol(sym.RPAREN); }
+"+"                  { return new Symbol(PLUS); }
+"-"                  { return new Symbol(MINUS); }
+"*"                  { return new Symbol(TIMES); }
+"/"                  { return new Symbol(DIV); }
+"("                  { return new Symbol(LPAREN); }
+")"                  { return new Symbol(RPAREN); }
 
 .                    { System.out.printf("unexpected char |%s|\n", yytext()); }