diff --git a/build.gradle b/build.gradle
index 22d81d67..9954559f 100644
--- a/build.gradle
+++ b/build.gradle
@@ -38,3 +38,7 @@ test{
 
 sourceSets.main.java.srcDirs = ["src"]
 sourceSets.test.java.srcDirs = ["test"]
+
+/* Set the minimum Java version compatibility: */
+sourceCompatibility = '1.7'
+targetCompatibility = '1.7'
diff --git a/buildADQL.xml b/buildADQL.xml
index af43f382..0038f7b7 100644
--- a/buildADQL.xml
+++ b/buildADQL.xml
@@ -35,6 +35,10 @@
 		<condition><not><isset property="JUNIT-API"/></not></condition>
 	</fail>
 	
+	<!-- JAVA VERSION COMPATIBILITY -->
+	<property name="ant.build.javac.source" value="1.7"/>
+	<property name="ant.build.javac.target" value="1.7"/>
+	
 	<!-- CLASSPATHS -->
 	<path id="adql.classpath">
 		<pathelement location="${POSTGRES}" />
diff --git a/buildUWS.xml b/buildUWS.xml
index c2a05477..6f4c4de4 100644
--- a/buildUWS.xml
+++ b/buildUWS.xml
@@ -40,6 +40,10 @@
 	<fail message="The property SERVLET-API must be set! It provides the path toward a directory or a JAR which contains all classes inside javax.servlet.">
 		<condition><not><isset property="SERVLET-API"/></not></condition>
 	</fail>
+	
+	<!-- JAVA VERSION COMPATIBILITY -->
+	<property name="ant.build.javac.source" value="1.7"/>
+	<property name="ant.build.javac.target" value="1.7"/>
 
 	<!-- CLASSPATHS -->
 	<path id="uws.classpath">