diff --git a/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemePreferences.java b/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemePreferences.java
index 6c8f84d556..75edc6f2ec 100644
--- a/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemePreferences.java
+++ b/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemePreferences.java
@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -47,8 +47,15 @@ public class ThemePreferences {
 		else if (themeId.startsWith(DiscoverableGTheme.CLASS_PREFIX)) {
 			String className = themeId.substring(DiscoverableGTheme.CLASS_PREFIX.length());
 			try {
-				Class<?> forName = Class.forName(className);
-				return (GTheme) forName.getDeclaredConstructor().newInstance();
+				ClassLoader loader = getClass().getClassLoader();
+				Class<?> clazz = Class.forName(className, false, loader);
+				if (!GTheme.class.isAssignableFrom(clazz)) {
+					Msg.showError(GTheme.class, null, "Can't Load Previous Theme",
+						"Theme class name does not point to a GTheme instance: " + className);
+					return ThemeManager.getDefaultTheme();
+				}
+
+				return (GTheme) clazz.getDeclaredConstructor().newInstance();
 			}
 			catch (Exception e) {
 				Msg.showError(GTheme.class, null, "Can't Load Previous Theme",
diff --git a/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemeReader.java b/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemeReader.java
index eae40ccdd3..e6db3bd083 100644
--- a/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemeReader.java
+++ b/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemeReader.java
@@ -135,7 +135,15 @@ class ThemeReader extends AbstractThemeReader {
 		int indexOf = path.indexOf("images/");
 		if (indexOf < 0) {
 			Msg.error(this, "Unknown file: " + path);
+			return;
 		}
+
+		if (path.contains("..")) {
+			// We write the theme images to an 'images' dir under the zip root.  No need for '..'
+			Msg.error(this, "Zip paths with '..' not allowed: " + path);
+			return;
+		}
+
 		String relativePath = path.substring(indexOf, path.length());
 		File dir = Application.getUserSettingsDirectory();
 		File iconFile = new File(dir, relativePath);
diff --git a/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemeWriter.java b/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemeWriter.java
index 45f49ed5e6..bfee835d31 100644
--- a/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemeWriter.java
+++ b/Ghidra/Framework/Gui/src/main/java/generic/theme/ThemeWriter.java
@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -122,12 +122,17 @@ public class ThemeWriter {
 	}
 
 	private void copyToZipFile(String dir, File iconFile, ZipOutputStream zos) throws IOException {
+		// dir:        MyTheme.theme/
+		// zip name:   MyTheme.theme/images/myicon.png
 		ZipEntry entry = new ZipEntry(dir + "images/" + iconFile.getName());
 		zos.putNextEntry(entry);
 		Files.copy(iconFile.toPath(), zos);
 	}
 
 	private void saveThemeFileToZip(String dir, ZipOutputStream zos) throws IOException {
+		// dir:        MyTheme.theme/
+		// theme name: MyTheme
+		// zip name:   MyTheme.theme/MyTheme.theme
 		ZipEntry entry = new ZipEntry(dir + theme.getName() + ".theme");
 		zos.putNextEntry(entry);
 		BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(zos));