diff --git a/build.xml b/build.xml
index 1c8caa19e..3088cf58f 100644
--- a/build.xml
+++ b/build.xml
@@ -34,14 +34,18 @@ build.sysclasspath=ignore
 
     <target name="init">
         <!-- Create the build directory structure used by compile -->
-        <mkdir dir="${build.dir}/gen/org/antlr/v4" />
+        <property name="antlr3.gen.dir" value="${build.dir}/generated-sources/antlr3" />
+        <mkdir dir="${antlr3.gen.dir}" />
     </target>
 
 	<target name="antlr" depends="init">
 		<echo>parse grammars</echo>
 		<java classname="org.antlr.Tool" fork="true" failonerror="true" maxmemory="300m"
 			dir="${basedir}/tool/src/org/antlr/v4/parse">
+			<arg value="-verbose"/>
 			<arg value="-make"/>
+			<arg value="-o"/>
+			<arg value="${antlr3.gen.dir}/org/antlr/v4/parse"/>
 			<arg value="ANTLRParser.g"/>
 			<arg value="ANTLRLexer.g"/>
 			<arg value="ActionSplitter.g"/>
@@ -58,9 +62,12 @@ build.sysclasspath=ignore
 		<echo>codegen grammars</echo>
 		<java classname="org.antlr.Tool" fork="true" failonerror="true" maxmemory="300m"
 			dir="${basedir}/tool/src/org/antlr/v4/codegen">
+			<arg value="-verbose"/>
 			<arg value="-make"/>
+			<arg value="-o"/>
+			<arg value="${antlr3.gen.dir}/org/antlr/v4/codegen"/>
 			<arg value="-lib"/>
-			<arg value="../parse"/>
+			<arg value="${antlr3.gen.dir}/org/antlr/v4/parse"/>
 			<arg value="SourceGenTriggers.g"/>
 			<classpath>
 				<pathelement location="${antlr3.jar}"/>
@@ -87,7 +94,7 @@ build.sysclasspath=ignore
             <compilerarg value="-Xlint"/>
             <compilerarg value="-Xlint:-serial"/>
             <classpath refid="classpath"/>
-            <src path="${build.dir}/src:${build.dir}/gen"/>
+            <src path="${build.dir}/src:${antlr3.gen.dir}"/>
         </javac>
     </target>