diff --git a/build.xml b/build.xml
index 57f848ea33d..df27775dbbe 100644
--- a/build.xml
+++ b/build.xml
@@ -68,6 +68,10 @@
     </subant>
   </target>
 
+  <target name="beast">
+    <fail message="The Beast only works inside of individual modules"/>
+  </target>
+
   <target name="documentation" description="Generate Lucene and Solr Documentation">
     <subant target="documentation" inheritall="false" failonerror="true">
       <fileset dir="lucene" includes="build.xml" />
diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 870cf2a8255..4ceb500521e 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -313,6 +313,9 @@ Tests
   Some of the slow Monster tests now explicitly choose the default codec.
   (Mike McCandless, Shawn Heisey)
 
+* LUCENE-5968: Improve error message when 'ant beast' is run on top-level
+  modules.  (Ramkumar Aiyengar, Uwe Schindler)
+
 Optimizations
 
 * LUCENE-5960: Use a more efficient bitset, not a Set<Integer>, to
diff --git a/lucene/analysis/build.xml b/lucene/analysis/build.xml
index e77cfdfcf2a..0abd60ae6b6 100644
--- a/lucene/analysis/build.xml
+++ b/lucene/analysis/build.xml
@@ -105,6 +105,9 @@
   <target name="test">
     <forall-analyzers target="test"/>
   </target>
+  <target name="beast">
+    <fail message="The Beast only works inside of individual modules"/>
+  </target>
   <target name="jar">
     <forall-analyzers target="jar-core"/>
   </target>
diff --git a/lucene/build.xml b/lucene/build.xml
index a4f107b47ca..c1e0971fdab 100644
--- a/lucene/build.xml
+++ b/lucene/build.xml
@@ -60,6 +60,10 @@
           description="Runs pitests (core, modules and back-compat)"
   />
 
+  <target name="beast">
+    <fail message="The Beast only works inside of individual modules"/>
+  </target>
+
   <target name="compile-core" depends="compile-lucene-core"/>
 
   <!-- lucene/test-framework is excluded from compilation -->
diff --git a/lucene/common-build.xml b/lucene/common-build.xml
index ac6e1c4f757..c7975d30a90 100644
--- a/lucene/common-build.xml
+++ b/lucene/common-build.xml
@@ -1351,6 +1351,11 @@ ${tests-output}/junit4-*.suites     - per-JVM executed suites
 
   <!-- Beast the actual tests (must be wrapped with -init-totals, -check-totals) -->
   <target name="-beast" depends="resolve-groovy">
+    <fail message="The Beast only works inside of individual modules (where 'junit.classpath' is defined)">
+      <condition>
+        <not><isreference refid="junit.classpath"/></not>
+      </condition>
+    </fail>
     <groovy taskname="beaster"><![CDATA[
       import org.apache.tools.ant.BuildException;
       import org.apache.tools.ant.BuildLogger;
diff --git a/solr/build.xml b/solr/build.xml
index 1404f5baa43..8a591ab2104 100644
--- a/solr/build.xml
+++ b/solr/build.xml
@@ -133,6 +133,9 @@
           depends="-clover.load, test-solr-core, test-solrj"/>
   <target name="pitest" description="Validate, then run core, solrj, and contrib unit tests."
           depends="pitest-core, pitest-contrib"/>
+  <target name="beast">
+    <fail message="The Beast only works inside of individual modules"/>
+  </target>
   <target name="compile-test" description="Compile core, solrj, and contrib unit tests, and solr-test-framework."
           depends="compile-solr-test-framework, compile-test-solr-core, compile-test-solrj, compile-test-contrib"/>
   <target name="javadocs" description="Calls javadocs-all, javadocs-solrj, and javadocs-test-framework"