diff --git a/core/src/main/java/com/webcohesion/enunciate/Enunciate.java b/core/src/main/java/com/webcohesion/enunciate/Enunciate.java
index d36b30695..9aa1da7af 100644
--- a/core/src/main/java/com/webcohesion/enunciate/Enunciate.java
+++ b/core/src/main/java/com/webcohesion/enunciate/Enunciate.java
@@ -585,7 +585,7 @@ public void run() {
       getLogger().debug("Detected API Types: %s", new EnunciateLogger.ListWriter(includedTypes));
 
       //gather all the java source files.
-      List<URL> sourceFiles = getSourceFileURLs();
+      Set<URL> sourceFiles = getSourceFileURLs();
       URLClassLoader apiClassLoader = new URLClassLoader(scanpath.toArray(new URL[0]));
       for (String javaFile : scannedSourceFiles) {
 
@@ -771,8 +771,8 @@ public String writeClasspath(List<File> cp) {
     return builder.toString();
   }
 
-  protected List<URL> getSourceFileURLs() {
-    List<URL> sourceFiles = new ArrayList<>(this.sourceFiles.size());
+  protected Set<URL> getSourceFileURLs() {
+    Set<URL> sourceFiles = new HashSet<>(this.sourceFiles.size());
     for (File sourceFile : this.sourceFiles) {
       try {
         sourceFiles.add(sourceFile.toURI().toURL());