diff --git a/maven-model-builder/src/main/java/org/apache/maven/model/validation/DefaultModelValidator.java b/maven-model-builder/src/main/java/org/apache/maven/model/validation/DefaultModelValidator.java
index 0571677ce1..96cdb4be00 100644
--- a/maven-model-builder/src/main/java/org/apache/maven/model/validation/DefaultModelValidator.java
+++ b/maven-model-builder/src/main/java/org/apache/maven/model/validation/DefaultModelValidator.java
@@ -261,10 +261,8 @@ public class DefaultModelValidator
 
                     validateStringNotEmpty( "build.plugins.plugin.groupId", problems, Severity.ERROR, p.getGroupId() );
 
-                    validateStringNotEmpty( "build.plugins.plugin.version", problems, errOn31, p.getVersion(),
-                                            p.getKey() );
-
-                    validatePluginVersion( "build.plugins.plugin.version", problems, errOn30, p.getVersion(), p.getKey() );
+                    validatePluginVersion( "build.plugins.plugin.version", problems, p.getVersion(), p.getKey(),
+                                           request );
 
                     validateBoolean( "build.plugins.plugin.inherited", problems, errOn30, p.getInherited(),
                                      p.getKey() );
@@ -655,27 +653,31 @@ public class DefaultModelValidator
         return false;
     }
 
-    private boolean validatePluginVersion( String fieldName, ModelProblemCollector problems, Severity severity, String string,
-                                     String sourceHint )
+    private boolean validatePluginVersion( String fieldName, ModelProblemCollector problems, String string,
+                                           String sourceHint, ModelBuildingRequest request )
     {
-        if ( string == null || string.length() <= 0 )
+        Severity errOn30 = getSeverity( request, ModelBuildingRequest.VALIDATION_LEVEL_MAVEN_3_0 );
+        Severity errOn31 = getSeverity( request, ModelBuildingRequest.VALIDATION_LEVEL_MAVEN_3_1 );
+
+        if ( !validateNotNull( fieldName, problems, errOn31, string, sourceHint ) )
         {
-            return true;
+            return false;
         }
 
-        if ( !hasExpression( string ) && !"RELEASE".equals( string ) && !"LATEST".equals( string ) )
+        if ( string.length() > 0 && !hasExpression( string ) && !"RELEASE".equals( string )
+            && !"LATEST".equals( string ) )
         {
             return true;
         }
 
         if ( sourceHint != null )
         {
-            addViolation( problems, severity, "'" + fieldName + "' must be a valid version for " + sourceHint
+            addViolation( problems, errOn30, "'" + fieldName + "' must be a valid version for " + sourceHint
                 + " but is '" + string + "'." );
         }
         else
         {
-            addViolation( problems, severity, "'" + fieldName + "' must be a valid version but is '" + string + "'." );
+            addViolation( problems, errOn30, "'" + fieldName + "' must be a valid version but is '" + string + "'." );
         }
 
         return false;
@@ -693,7 +695,12 @@ public class DefaultModelValidator
 
     private static Severity getSeverity( ModelBuildingRequest request, int errorThreshold )
     {
-        if ( request.getValidationLevel() < errorThreshold )
+        return getSeverity( request.getValidationLevel(), errorThreshold );
+    }
+
+    private static Severity getSeverity( int validationLevel, int errorThreshold )
+    {
+        if ( validationLevel < errorThreshold )
         {
             return Severity.WARNING;
         }
diff --git a/maven-model-builder/src/test/java/org/apache/maven/model/validation/DefaultModelValidatorTest.java b/maven-model-builder/src/test/java/org/apache/maven/model/validation/DefaultModelValidatorTest.java
index 9e21926c4e..3d066690bf 100644
--- a/maven-model-builder/src/test/java/org/apache/maven/model/validation/DefaultModelValidatorTest.java
+++ b/maven-model-builder/src/test/java/org/apache/maven/model/validation/DefaultModelValidatorTest.java
@@ -286,6 +286,17 @@ public class DefaultModelValidatorTest
         assertViolations( result, 0, 0, 1 );
     }
 
+    public void testEmptyPluginVersion()
+        throws Exception
+    {
+        SimpleProblemCollector result = validate( "empty-plugin-version.xml" );
+
+        assertViolations( result, 0, 1, 0 );
+
+        assertEquals( "'build.plugins.plugin.version' must be a valid version "
+            + "for org.apache.maven.plugins:maven-it-plugin but is ''.", result.getErrors().get( 0 ) );
+    }
+
     public void testMissingRepositoryId()
         throws Exception
     {
diff --git a/maven-model-builder/src/test/resources/poms/validation/empty-plugin-version.xml b/maven-model-builder/src/test/resources/poms/validation/empty-plugin-version.xml
new file mode 100644
index 0000000000..340efc5cd3
--- /dev/null
+++ b/maven-model-builder/src/test/resources/poms/validation/empty-plugin-version.xml
@@ -0,0 +1,34 @@
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+<project>
+  <modelVersion>4.0.0</modelVersion>
+  <artifactId>foo</artifactId>
+  <groupId>bar</groupId>
+  <version>1.0</version>
+  <packaging>pack</packaging>
+  <build>
+    <plugins>
+      <plugin>
+        <artifactId>maven-it-plugin</artifactId>
+        <version></version>
+      </plugin>
+    </plugins>
+  </build>
+</project>