diff --git a/build.xml b/build.xml
index 0cfed881ffd..4d5f70d36ef 100644
--- a/build.xml
+++ b/build.xml
@@ -239,7 +239,7 @@
 
     <target name="preloader">
       <cleandir dir="${output}/classes/preloader"/>
-      <javac2 destdir="${output}/classes/preloader" debug="true" debuglevel="lines,vars,source" includeAntRuntime="false" target="${java.target}">
+      <javac2 destdir="${output}/classes/preloader" debug="true" debuglevel="lines,vars,source" includeAntRuntime="false" source="${java.target}" target="${java.target}">
           <src refid="preloaderSources.path"/>
       </javac2>
 
@@ -309,7 +309,7 @@
 
         <cleandir dir="${output}/classes/compiler"/>
 
-        <javac2 destdir="${output}/classes/compiler" debug="true" debuglevel="lines,vars,source" includeAntRuntime="false"  target="${java.target}">
+        <javac2 destdir="${output}/classes/compiler" debug="true" debuglevel="lines,vars,source" includeAntRuntime="false" source="${java.target}" target="${java.target}">
             <withKotlin/>
             <src refid="compilerSources.path"/>
             <classpath refid="classpath"/>
@@ -434,7 +434,7 @@
 
     <target name="antTools">
         <cleandir dir="${output}/classes/buildTools"/>
-        <javac2 destdir="${output}/classes/buildTools" debug="true" debuglevel="lines,vars,source" includeAntRuntime="false" target="${java.target}">
+        <javac2 destdir="${output}/classes/buildTools" debug="true" debuglevel="lines,vars,source" includeAntRuntime="false" source="${java.target}" target="${java.target}">
             <src>
                 <dirset dir="${basedir}/build-tools">
                     <include name="core/src"/>
@@ -502,7 +502,7 @@
     <target name="annotationsExt">
         <cleandir dir="${output}/classes/annotations-ext"/>
 
-        <javac2 destdir="${output}/classes/annotations-ext" debug="true" debuglevel="lines,vars,source" includeAntRuntime="false" target="${java.target}">
+        <javac2 destdir="${output}/classes/annotations-ext" debug="true" debuglevel="lines,vars,source" includeAntRuntime="false" source="${java.target}" target="${java.target}">
             <src path="${basedir}/compiler/annotations-ext/src"/>
         </javac2>
 
@@ -522,7 +522,7 @@
 
     <target name="runtime">
         <cleandir dir="${output}/classes/runtime"/>
-        <javac2 destdir="${output}/classes/runtime" debug="true" debuglevel="lines,vars,source" includeAntRuntime="false" target="${java.target}">
+        <javac2 destdir="${output}/classes/runtime" debug="true" debuglevel="lines,vars,source" includeAntRuntime="false" source="${java.target}" target="${java.target}">
             <src path="${basedir}/runtime/src"/>
         </javac2>