diff --git a/src/main/java/dan200/computercraft/ComputerCraft.java b/src/main/java/dan200/computercraft/ComputerCraft.java
index 741403964c..77c344db0d 100644
--- a/src/main/java/dan200/computercraft/ComputerCraft.java
+++ b/src/main/java/dan200/computercraft/ComputerCraft.java
@@ -928,7 +928,7 @@ public static IMount createResourceMount( Class<?> modClass, String domain, Stri
                 FileSystem fs = FileSystems.newFileSystem( modJar.toPath(), ComputerCraft.class.getClassLoader() );
                 mounts.add( new FileSystemMount( fs, subPath ) );
             }
-            catch( IOException | ProviderNotFoundException | ServiceConfigurationError e )
+            catch( IOException | RuntimeException | ServiceConfigurationError e )
             {
                 ComputerCraft.log.error( "Could not load mount from mod jar", e );
                 // Ignore
@@ -940,16 +940,16 @@ public static IMount createResourceMount( Class<?> modClass, String domain, Stri
         if( resourcePackDir.exists() && resourcePackDir.isDirectory() )
         {
             String[] resourcePacks = resourcePackDir.list();
-            for( String resourcePack1 : resourcePacks )
+            for( String resourcePackName : resourcePacks )
             {
                 try
                 {
-                    File resourcePack = new File( resourcePackDir, resourcePack1 );
+                    File resourcePack = new File( resourcePackDir, resourcePackName );
                     if( !resourcePack.isDirectory() )
                     {
                         // Mount a resource pack from a jar
-                        IMount resourcePackMount = new FileSystemMount( FileSystems.getFileSystem( resourcePack.toURI() ), subPath );
-                        mounts.add( resourcePackMount );
+                        FileSystem fs = FileSystems.newFileSystem( resourcePack.toPath(), ComputerCraft.class.getClassLoader() );
+                        mounts.add( new FileSystemMount( fs, subPath ) );
                     }
                     else
                     {
@@ -962,9 +962,9 @@ public static IMount createResourceMount( Class<?> modClass, String domain, Stri
                         }
                     }
                 }
-                catch( IOException e )
+                catch( IOException | RuntimeException | ServiceConfigurationError e )
                 {
-                    ComputerCraft.log.error( "Could not load resource pack '" + resourcePack1 + "'", e );
+                    ComputerCraft.log.error( "Could not load resource pack '" + resourcePackName + "'", e );
                 }
             }
         }
diff --git a/src/main/java/dan200/computercraft/core/apis/handles/BinaryReadableHandle.java b/src/main/java/dan200/computercraft/core/apis/handles/BinaryReadableHandle.java
index d9078ab000..33d57a42b8 100644
--- a/src/main/java/dan200/computercraft/core/apis/handles/BinaryReadableHandle.java
+++ b/src/main/java/dan200/computercraft/core/apis/handles/BinaryReadableHandle.java
@@ -33,7 +33,7 @@ public BinaryReadableHandle( ReadableByteChannel channel, Closeable closeable )
     {
         super( closeable );
         this.m_reader = channel;
-        this.m_seekable = channel instanceof SeekableByteChannel ? (SeekableByteChannel) channel : null;
+        this.m_seekable = asSeekable( channel );
     }
 
     public BinaryReadableHandle( ReadableByteChannel channel )
diff --git a/src/main/java/dan200/computercraft/core/apis/handles/BinaryWritableHandle.java b/src/main/java/dan200/computercraft/core/apis/handles/BinaryWritableHandle.java
index b377c4a104..8502245082 100644
--- a/src/main/java/dan200/computercraft/core/apis/handles/BinaryWritableHandle.java
+++ b/src/main/java/dan200/computercraft/core/apis/handles/BinaryWritableHandle.java
@@ -27,7 +27,7 @@ public BinaryWritableHandle( WritableByteChannel channel, Closeable closeable )
     {
         super( closeable );
         this.m_writer = channel;
-        this.m_seekable = channel instanceof SeekableByteChannel ? (SeekableByteChannel) channel : null;
+        this.m_seekable = asSeekable( channel );
     }
 
     public BinaryWritableHandle( WritableByteChannel channel )
diff --git a/src/main/java/dan200/computercraft/core/apis/handles/HandleGeneric.java b/src/main/java/dan200/computercraft/core/apis/handles/HandleGeneric.java
index 44d14505b7..19b70f4c29 100644
--- a/src/main/java/dan200/computercraft/core/apis/handles/HandleGeneric.java
+++ b/src/main/java/dan200/computercraft/core/apis/handles/HandleGeneric.java
@@ -6,6 +6,7 @@
 import javax.annotation.Nonnull;
 import java.io.Closeable;
 import java.io.IOException;
+import java.nio.channels.Channel;
 import java.nio.channels.SeekableByteChannel;
 
 import static dan200.computercraft.core.apis.ArgumentHelper.optInt;
@@ -69,15 +70,31 @@ protected static Object[] handleSeek( SeekableByteChannel channel, Object[] args
                     throw new LuaException( "bad argument #1 to 'seek' (invalid option '" + whence + "'" );
             }
 
-            return new Object[] { channel.position() };
+            return new Object[]{ channel.position() };
         }
         catch( IllegalArgumentException e )
         {
-            return new Object[] { false, "Position is negative" };
+            return new Object[]{ false, "Position is negative" };
         }
         catch( IOException e )
         {
             return null;
         }
     }
+
+    protected static SeekableByteChannel asSeekable( Channel channel )
+    {
+        if( !(channel instanceof SeekableByteChannel) ) return null;
+
+        SeekableByteChannel seekable = (SeekableByteChannel) channel;
+        try
+        {
+            seekable.position( seekable.position() );
+            return seekable;
+        }
+        catch( IOException | UnsupportedOperationException e )
+        {
+            return null;
+        }
+    }
 }