diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/activities/CustomFilePickerActivity.java b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/activities/CustomFilePickerActivity.java
deleted file mode 100644
index 29a968d50c..0000000000
--- a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/activities/CustomFilePickerActivity.java
+++ /dev/null
@@ -1,51 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-package org.dolphinemu.dolphinemu.activities;
-
-import android.content.Intent;
-import android.os.Bundle;
-import android.os.Environment;
-
-import androidx.annotation.Nullable;
-
-import com.nononsenseapps.filepicker.AbstractFilePickerFragment;
-import com.nononsenseapps.filepicker.FilePickerActivity;
-
-import org.dolphinemu.dolphinemu.fragments.CustomFilePickerFragment;
-
-import java.io.File;
-import java.util.HashSet;
-
-public class CustomFilePickerActivity extends FilePickerActivity
-{
-  public static final String EXTRA_EXTENSIONS = "dolphinemu.org.filepicker.extensions";
-
-  private HashSet<String> mExtensions;
-
-  @Override
-  protected void onCreate(Bundle savedInstanceState)
-  {
-    super.onCreate(savedInstanceState);
-
-    Intent intent = getIntent();
-    if (intent != null)
-    {
-      mExtensions = (HashSet<String>) intent.getSerializableExtra(EXTRA_EXTENSIONS);
-    }
-  }
-
-  @Override
-  protected AbstractFilePickerFragment<File> getFragment(
-          @Nullable final String startPath, final int mode, final boolean allowMultiple,
-          final boolean allowCreateDir, final boolean allowExistingFile,
-          final boolean singleClick)
-  {
-    CustomFilePickerFragment fragment = new CustomFilePickerFragment();
-    // startPath is allowed to be null. In that case, default folder should be SD-card and not "/"
-    fragment.setArgs(
-            startPath != null ? startPath : Environment.getExternalStorageDirectory().getPath(),
-            mode, allowMultiple, allowCreateDir, allowExistingFile, singleClick);
-    fragment.setExtensions(mExtensions);
-    return fragment;
-  }
-}
diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/activities/CustomFilePickerActivity.kt b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/activities/CustomFilePickerActivity.kt
new file mode 100644
index 0000000000..3b48c62f12
--- /dev/null
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/activities/CustomFilePickerActivity.kt
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package org.dolphinemu.dolphinemu.activities
+
+import android.os.Bundle
+import android.os.Environment
+import com.nononsenseapps.filepicker.AbstractFilePickerFragment
+import com.nononsenseapps.filepicker.FilePickerActivity
+import org.dolphinemu.dolphinemu.fragments.CustomFilePickerFragment
+import java.io.File
+
+class CustomFilePickerActivity : FilePickerActivity() {
+    private var extensions: HashSet<String>? = null
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        if (intent != null) {
+            extensions = intent.getSerializableExtra(EXTRA_EXTENSIONS) as HashSet<String>?
+        }
+    }
+
+    override fun getFragment(
+        startPath: String?,
+        mode: Int,
+        allowMultiple: Boolean,
+        allowCreateDir: Boolean,
+        allowExistingFile: Boolean,
+        singleClick: Boolean
+    ): AbstractFilePickerFragment<File> {
+        val fragment = CustomFilePickerFragment()
+        // startPath is allowed to be null. In that case, default folder should be SD-card and not "/"
+        fragment.setArgs(
+            startPath ?: Environment.getExternalStorageDirectory().path,
+            mode,
+            allowMultiple,
+            allowCreateDir,
+            allowExistingFile,
+            singleClick
+        )
+        fragment.setExtensions(extensions)
+        return fragment
+    }
+
+    companion object {
+        const val EXTRA_EXTENSIONS = "dolphinemu.org.filepicker.extensions"
+    }
+}