diff --git a/src/main/java/org/apache/maven/plugins/pmd/exec/Executor.java b/src/main/java/org/apache/maven/plugins/pmd/exec/Executor.java
index ca17511e..b4636d15 100644
--- a/src/main/java/org/apache/maven/plugins/pmd/exec/Executor.java
+++ b/src/main/java/org/apache/maven/plugins/pmd/exec/Executor.java
@@ -25,8 +25,11 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
 import java.net.URL;
 import java.net.URLClassLoader;
+import java.net.URLDecoder;
+import java.nio.charset.StandardCharsets;
 import java.util.logging.Handler;
 import java.util.logging.Level;
 import java.util.logging.SimpleFormatter;
@@ -125,17 +128,23 @@ protected static String buildClasspath()
         return classpath.toString();
     }
 
-    private static void buildClasspath( StringBuilder classpath, ClassLoader cl )
+    static void buildClasspath( StringBuilder classpath, ClassLoader cl )
     {
         if ( cl instanceof URLClassLoader )
         {
             for ( URL url : ( (URLClassLoader) cl ).getURLs() )
             {
-                String urlString = url.toString();
-                if ( urlString.startsWith( "file:" ) )
+                if ( "file".equalsIgnoreCase( url.getProtocol() ) )
                 {
-                    String f = urlString.substring( 5 ); //  strip "file:"
-                    classpath.append( f ).append( File.pathSeparatorChar );
+                    try
+                    {
+                        String filename = URLDecoder.decode( url.getPath(), StandardCharsets.UTF_8.name() );
+                        classpath.append( new File( filename ).getPath() ).append( File.pathSeparatorChar );
+                    }
+                    catch ( UnsupportedEncodingException e )
+                    {
+                        LOG.warn( "Ignoring " + url + " in classpath due to UnsupportedEncodingException", e );
+                    }
                 }
             }
         }
diff --git a/src/test/java/org/apache/maven/plugins/pmd/exec/ExecutorTest.java b/src/test/java/org/apache/maven/plugins/pmd/exec/ExecutorTest.java
new file mode 100644
index 00000000..67dad92c
--- /dev/null
+++ b/src/test/java/org/apache/maven/plugins/pmd/exec/ExecutorTest.java
@@ -0,0 +1,48 @@
+package org.apache.maven.plugins.pmd.exec;
+
+/*
+ * 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.
+ */
+
+import java.io.File;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
+
+import org.apache.commons.lang3.SystemUtils;
+import org.junit.Assert;
+
+import junit.framework.TestCase;
+
+public class ExecutorTest extends TestCase
+{
+    public void testBuildClasspath() throws MalformedURLException {
+        String basename = "home/test/dir with space/mylib.jar";
+        String pathname = new File("/", basename).getPath();
+        if ( SystemUtils.IS_OS_WINDOWS )
+        {
+            pathname = new File( File.listRoots()[0], basename ).getPath();
+        }
+        URL[] urls = new URL[] { new File(pathname).toURI().toURL() };
+        URLClassLoader mockedClassLoader = new URLClassLoader( urls );
+
+        StringBuilder classpath = new StringBuilder();
+        Executor.buildClasspath(classpath, mockedClassLoader);
+        Assert.assertEquals( pathname + File.pathSeparator, classpath.toString() );
+    }
+}