diff --git a/src/main/java/systems/crigges/jmpq3/JMpqEditor.java b/src/main/java/systems/crigges/jmpq3/JMpqEditor.java
index bbbe910..992eff9 100644
--- a/src/main/java/systems/crigges/jmpq3/JMpqEditor.java
+++ b/src/main/java/systems/crigges/jmpq3/JMpqEditor.java
@@ -209,6 +209,40 @@ private void readAttributesFile() {
         }
     }
 
+    /**
+     * For use when the MPQ is missing a (listfile)
+     * Adds this custom listfile into the MPQ and uses it
+     * for rebuilding purposes.
+     * If this is not a full listfile, the end result will be missing files.
+     *
+     * @param externalListfilePath  Path to a file containing listfile entries
+     */
+    public void setExternalListfile(File externalListfilePath) {
+        if(!canWrite) {
+            log.warn("The mpq was opened as readonly, setting an external listfile will have no effect.");
+            return;
+        }
+        if(!externalListfilePath.exists()) {
+            log.warn("External MPQ File: " + externalListfilePath.getAbsolutePath() +
+                " does not exist and will not be used");
+            return;
+        }
+        try {
+            // Read and apply listfile
+            listFile = new Listfile(Files.readAllBytes(externalListfilePath.toPath()));
+            checkListfileEntries();
+            // Operation succeeded and added a listfile so we can now write properly.
+            // (as long as it wasn't read-only to begin with)
+        } catch (Exception ex) {
+            log.warn("Could not apply external listfile: " + externalListfilePath.getAbsolutePath());
+            // The value of canWrite is not changed intentionally
+        }
+    }
+
+    /**
+     * Reads an internal Listfile name called (listfile)
+     * and applies that as the archive's listfile.
+     */
     private void readListFile() {
         if (hasFile("(listfile)")) {
             try {
@@ -216,18 +250,7 @@ private void readListFile() {
                 tempFile.deleteOnExit();
                 extractFile("(listfile)", tempFile);
                 listFile = new Listfile(Files.readAllBytes(tempFile.toPath()));
-                int hiddenFiles = (hasFile("(attributes)") ? 2 : 1) + (hasFile("(signature)") ? 1 : 0);
-                if (canWrite) {
-                    if (listFile.getFiles().size() >= blockTable.getAllVaildBlocks().size() - hiddenFiles) {
-                        log.warn("mpq's listfile is incomplete. Blocks without listfile entry will be discarded");
-                    }
-                    for (String fileName : listFile.getFiles()) {
-                        if (!hasFile(fileName)) {
-                            log.warn("listfile entry does not exist in archive and will be discarded: " + fileName);
-                        }
-                    }
-                    listFile.getFileMap().entrySet().removeIf(file -> !hasFile(file.getValue()));
-                }
+                checkListfileEntries();
             } catch (Exception e) {
                 log.warn("Extracting the mpq's listfile failed. It cannot be rebuild.", e);
             }
@@ -237,6 +260,37 @@ private void readListFile() {
         }
     }
 
+    /**
+     * Performs verification to see if we know all the blocks of this file.
+     * Prints warnings if we don't know all blocks.
+     *
+     * @throws JMpqException    If retrieving valid blocks fails
+     */
+    private void checkListfileEntries() throws JMpqException {
+        int hiddenFiles = (hasFile("(attributes)") ? 2 : 1) + (hasFile("(signature)") ? 1 : 0);
+        if (canWrite) {
+            checkListfileCompleteness(hiddenFiles);
+        }
+    }
+
+    /**
+     * Checks listfile for completeness against block table
+     *
+     * @param hiddenFiles  Num. hidden files
+     * @throws JMpqException    If retrieving valid blocks fails
+     */
+    private void checkListfileCompleteness(int hiddenFiles) throws JMpqException {
+        if (listFile.getFiles().size() <= blockTable.getAllVaildBlocks().size() - hiddenFiles) {
+            log.warn("mpq's listfile is incomplete. Blocks without listfile entry will be discarded");
+        }
+        for (String fileName : listFile.getFiles()) {
+            if (!hasFile(fileName)) {
+                log.warn("listfile entry does not exist in archive and will be discarded: " + fileName);
+            }
+        }
+        listFile.getFileMap().entrySet().removeIf(file -> !hasFile(file.getValue()));
+    }
+
     private void readBlockTable() throws IOException {
         ByteBuffer blockBuffer = ByteBuffer.allocate(blockSize * 16).order(ByteOrder.LITTLE_ENDIAN);
         fc.position(headerOffset + blockPos);
@@ -1046,4 +1100,13 @@ public String toString() {
         return "JMpqEditor [headerSize=" + headerSize + ", archiveSize=" + archiveSize + ", formatVersion=" + formatVersion + ", discBlockSize=" + discBlockSize
                 + ", hashPos=" + hashPos + ", blockPos=" + blockPos + ", hashSize=" + hashSize + ", blockSize=" + blockSize + ", hashMap=" + hashTable + "]";
     }
+
+    /**
+     * Returns an unmodifiable collection of all Listfile entries
+     *
+     * @return  Listfile entries
+     */
+    public Collection<String> getListfileEntries() {
+        return Collections.unmodifiableCollection(listFile.getFiles());
+    }
 }
diff --git a/src/test/java/systems/crigges/jmpq3test/MpqTests.java b/src/test/java/systems/crigges/jmpq3test/MpqTests.java
index 4c3a089..6bba7ce 100644
--- a/src/test/java/systems/crigges/jmpq3test/MpqTests.java
+++ b/src/test/java/systems/crigges/jmpq3test/MpqTests.java
@@ -20,8 +20,6 @@
 import java.nio.file.StandardCopyOption;
 import java.util.*;
 
-import static systems.crigges.jmpq3.HashTable.calculateFileKey;
-
 /**
  * Created by Frotty on 06.03.2017.
  */
@@ -136,6 +134,18 @@ public void testRebuild() throws IOException {
         }
     }
 
+    @Test
+    public void testExternalListfile() throws Exception {
+        File mpq = getFile("mpqs/normalMap.w3x");
+        File listFile = getFile("listfile.txt");
+        JMpqEditor mpqEditor = new JMpqEditor(mpq, MPQOpenOption.FORCE_V0);
+        if(mpqEditor.isCanWrite()) {
+            mpqEditor.deleteFile("(listfile)");
+        }
+        mpqEditor.setExternalListfile(listFile);
+        Assert.assertTrue(mpqEditor.getListfileEntries().contains("war3map.w3a"));
+    }
+
     @Test
     public void testRecompressBuild() throws IOException {
         File[] mpqs = getMpqs();
diff --git a/src/test/resources/listfile.txt b/src/test/resources/listfile.txt
new file mode 100644
index 0000000..89043f5
--- /dev/null
+++ b/src/test/resources/listfile.txt
@@ -0,0 +1,6 @@
+scripts\war3map.j
+war3map.j
+war3map.w3u
+war3map.w3t
+war3map.w3a
+customFile.j
\ No newline at end of file