diff --git a/skel_common/readme_changelog.txt b/skel_common/readme_changelog.txt
index cd16d35..b3e51b5 100644
--- a/skel_common/readme_changelog.txt
+++ b/skel_common/readme_changelog.txt
@@ -5,6 +5,8 @@ Changelog
 - Added a Validate warning for text files with LF line endings
 - Fixed data loss when decoding Windows-1252 text with accented characters
 - Changed catalog auto-update url from GMM's repository to SMM's
+- Added tolerance for non-standard zips containing backslash paths
+- Added a Validate warning for non-standard zips containing backslash paths
 
 1.0:
 - Changed mod list to a table with checkboxes
diff --git a/src/main/java/net/vhati/ftldat/FTLDat.java b/src/main/java/net/vhati/ftldat/FTLDat.java
index 9367395..cb2eef8 100644
--- a/src/main/java/net/vhati/ftldat/FTLDat.java
+++ b/src/main/java/net/vhati/ftldat/FTLDat.java
@@ -414,6 +414,7 @@ public class FTLDat {
 		 * The location it represents is not guaranteed to exist.
 		 */
 		public File getFile( String innerPath ) {
+			if ( innerPath.indexOf("\\") != -1 ) throw new IllegalArgumentException( "InnerPath contains backslashes: "+ innerPath );
 			return new File( rootDir, innerPath );
 		}
 	}
@@ -672,6 +673,7 @@ public class FTLDat {
 
 		@Override
 		public void add( String innerPath, InputStream is ) throws IOException {
+			if ( innerPath.indexOf("\\") != -1 ) throw new IllegalArgumentException( "InnerPath contains backslashes: "+ innerPath );
 			if ( pathToIndexMap.containsKey( innerPath ) ) {
 				throw new IOException( "InnerPath already exists: "+ innerPath );
 			}
@@ -716,6 +718,7 @@ public class FTLDat {
 
 		@Override
 		public void extractTo( String innerPath, OutputStream os ) throws FileNotFoundException, IOException {
+			if ( innerPath.indexOf("\\") != -1 ) throw new IllegalArgumentException( "InnerPath contains backslashes: "+ innerPath );
 			if ( !pathToIndexMap.containsKey( innerPath ) ) {
 				throw new FileNotFoundException( "InnerPath does not exist: "+ innerPath );
 			}
@@ -741,6 +744,7 @@ public class FTLDat {
 
 		@Override
 		public void remove( String innerPath ) throws FileNotFoundException, IOException {
+			if ( innerPath.indexOf("\\") != -1 ) throw new IllegalArgumentException( "InnerPath contains backslashes: "+ innerPath );
 			if ( !pathToIndexMap.containsKey( innerPath ) ) {
 				throw new FileNotFoundException( "InnerPath does not exist: "+ innerPath );
 			}
@@ -760,11 +764,13 @@ public class FTLDat {
 
 		@Override
 		public boolean contains( String innerPath ) {
+			if ( innerPath.indexOf("\\") != -1 ) throw new IllegalArgumentException( "InnerPath contains backslashes: "+ innerPath );
 			return pathToIndexMap.containsKey( innerPath );
 		}
 
 		@Override
 		public InputStream getInputStream( String innerPath ) throws FileNotFoundException, IOException {
+			if ( innerPath.indexOf("\\") != -1 ) throw new IllegalArgumentException( "InnerPath contains backslashes: "+ innerPath );
 			if ( !pathToIndexMap.containsKey( innerPath ) ) {
 				throw new FileNotFoundException( "InnerPath does not exist: "+ innerPath );
 			}
diff --git a/src/main/java/net/vhati/modmanager/core/ModPatchThread.java b/src/main/java/net/vhati/modmanager/core/ModPatchThread.java
index 4940364..b136cc9 100644
--- a/src/main/java/net/vhati/modmanager/core/ModPatchThread.java
+++ b/src/main/java/net/vhati/modmanager/core/ModPatchThread.java
@@ -190,9 +190,12 @@ public class ModPatchThread extends Thread {
 					while ( (item = zis.getNextEntry()) != null ) {
 						if ( item.isDirectory() ) continue;
 
-						Matcher m = pathPtn.matcher( item.getName() );
+						String innerPath = item.getName();
+						innerPath = innerPath.replace( '\\', '/' );  // Non-standard zips.
+
+						Matcher m = pathPtn.matcher( innerPath );
 						if ( !m.matches() ) {
-							log.warn( String.format( "Unexpected innerPath: %s", item.getName() ) );
+							log.warn( String.format( "Unexpected innerPath: %s", innerPath ) );
 							zis.closeEntry();
 							continue;
 						}
@@ -203,13 +206,13 @@ public class ModPatchThread extends Thread {
 
 						AbstractPack ftlP = topFolderMap.get( topFolder );
 						if ( ftlP == null ) {
-							log.warn( String.format( "Unexpected innerPath: %s", item.getName() ) );
+							log.warn( String.format( "Unexpected innerPath: %s", innerPath ) );
 							zis.closeEntry();
 							continue;
 						}
 
 						if ( fileName.endsWith( ".xml.append" ) || fileName.endsWith( ".append.xml" ) ) {
-							String innerPath = parentPath + fileName.replaceAll( "[.](?:xml[.]append|append[.]xml)$", ".xml" );
+							innerPath = parentPath + fileName.replaceAll( "[.](?:xml[.]append|append[.]xml)$", ".xml" );
 							innerPath = checkCase( innerPath, knownPaths, knownPathsLower );
 
 							if ( !ftlP.contains( innerPath ) ) {
@@ -234,7 +237,7 @@ public class ModPatchThread extends Thread {
 							}
 						}
 						else if ( fileName.endsWith( ".xml" ) || fileName.endsWith( ".txt" ) ) {
-							String innerPath = checkCase( item.getName(), knownPaths, knownPathsLower );
+							innerPath = checkCase( innerPath, knownPaths, knownPathsLower );
 
 							// Normalize line endings for other text files to CR-LF.
 							InputStream fixedStream = ModUtilities.setLineEndings( zis, "\r\n", modFile.getName()+":"+parentPath+fileName );
@@ -249,7 +252,7 @@ public class ModPatchThread extends Thread {
 							ftlP.add( innerPath, fixedStream );
 						}
 						else {
-							String innerPath = checkCase( item.getName(), knownPaths, knownPathsLower );
+							innerPath = checkCase( innerPath, knownPaths, knownPathsLower );
 
 							if ( !moddedItems.contains(innerPath) )
 								moddedItems.add( innerPath );
diff --git a/src/main/java/net/vhati/modmanager/core/ModUtilities.java b/src/main/java/net/vhati/modmanager/core/ModUtilities.java
index 45d9c15..672fd96 100644
--- a/src/main/java/net/vhati/modmanager/core/ModUtilities.java
+++ b/src/main/java/net/vhati/modmanager/core/ModUtilities.java
@@ -223,6 +223,15 @@ public class ModUtilities {
 				String innerPath = item.getName();
 				pendingMsgs.clear();
 
+				if ( innerPath.indexOf( "\\" ) != -1 ) {
+					pendingMsgs.add( new ReportMessage(
+						ReportMessage.ERROR,
+						String.format( "Backslashes in path. (Non-standard zip archive)" )
+					) );
+					modValid = false;
+					innerPath = innerPath.replace( '\\', '/' );
+				}
+
 				if ( !asciiEncoder.canEncode( innerPath ) ) {
 					pendingMsgs.add( new ReportMessage(
 						ReportMessage.ERROR,
@@ -379,9 +388,10 @@ public class ModUtilities {
 				}
 
 				if ( !pendingMsgs.isEmpty() ) {
+					// Prepend the original path.
 					messages.add( new ReportMessage(
 						ReportMessage.SUBSECTION,
-						innerPath
+						item.getName()
 					) );
 					messages.addAll( pendingMsgs );
 				}