diff --git a/enigma-swing/src/main/java/cuchaz/enigma/gui/elements/MenuBar.java b/enigma-swing/src/main/java/cuchaz/enigma/gui/elements/MenuBar.java
index b4808075..88fd687f 100644
--- a/enigma-swing/src/main/java/cuchaz/enigma/gui/elements/MenuBar.java
+++ b/enigma-swing/src/main/java/cuchaz/enigma/gui/elements/MenuBar.java
@@ -456,10 +456,11 @@ private static void prepareSaveMappingsAsMenu(JMenu saveMappingsAsMenu, JMenuIte
 							// Check that the file name ends with the extension.
 							String fileName = savePath.getFileName().toString();
 							String extension = format.getFileType().extension();
+							assert extension != null;
 
-							if (!fileName.endsWith("." + extension)) {
+							if (!fileName.endsWith(extension)) {
 								// If not, add the extension.
-								savePath = savePath.resolveSibling(fileName + "." + extension);
+								savePath = savePath.resolveSibling(fileName + extension);
 								// Store the adjusted file, so that it shows up properly
 								// the next time this dialog is used.
 								fileChooser.setSelectedFile(savePath.toFile());
diff --git a/enigma-swing/src/main/java/cuchaz/enigma/gui/util/ExtensionFileFilter.java b/enigma-swing/src/main/java/cuchaz/enigma/gui/util/ExtensionFileFilter.java
index a51bffbd..31c19530 100644
--- a/enigma-swing/src/main/java/cuchaz/enigma/gui/util/ExtensionFileFilter.java
+++ b/enigma-swing/src/main/java/cuchaz/enigma/gui/util/ExtensionFileFilter.java
@@ -12,6 +12,12 @@ public final class ExtensionFileFilter extends FileFilter {
 	private final String formatName;
 	private final List<String> extensions;
 
+	/**
+	 * Constructs an {@code ExtensionFileFilter}.
+	 *
+	 * @param formatName the human-readable name of the file format
+	 * @param extensions the file extensions with their leading dots (e.g. {@code .txt})
+	 */
 	public ExtensionFileFilter(String formatName, String... extensions) {
 		this.formatName = formatName;
 		this.extensions = List.of(extensions);
@@ -25,7 +31,7 @@ public boolean accept(File f) {
 		}
 
 		for (String extension : extensions) {
-			if (f.getName().endsWith("." + extension)) {
+			if (f.getName().endsWith(extension)) {
 				return true;
 			}
 		}
@@ -38,7 +44,7 @@ public String getDescription() {
 		var joiner = new StringJoiner(", ");
 
 		for (String extension : extensions) {
-			joiner.add("*." + extension);
+			joiner.add("*" + extension);
 		}
 
 		return I18n.translateFormatted("menu.file.mappings.file_filter", formatName, joiner.toString());
diff --git a/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingFormat.java b/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingFormat.java
index ae294237..22ab8dd5 100644
--- a/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingFormat.java
+++ b/enigma/src/main/java/cuchaz/enigma/translation/mapping/serde/MappingFormat.java
@@ -78,15 +78,15 @@ public FileType getFileType() {
 	 * A file type. It can be either a single file with an extension, or a directory
 	 * with a {@code null} extension.
 	 *
-	 * @param extension the file extension without the trailing dot {@code .}, or {@code null} for a directory
+	 * @param extension the file extension with the leading dot {@code .}, or {@code null} for a directory
 	 */
 	public record FileType(@Nullable String extension) {
 		public static final FileType DIRECTORY = new FileType(null);
-		public static final FileType MAPPING = new FileType("mapping");
-		public static final FileType SRG = new FileType("srg");
-		public static final FileType TINY = new FileType("tiny");
-		public static final FileType TXT = new FileType("txt");
-		public static final FileType ZIP = new FileType("zip");
+		public static final FileType MAPPING = new FileType(".mapping");
+		public static final FileType SRG = new FileType(".srg");
+		public static final FileType TINY = new FileType(".tiny");
+		public static final FileType TXT = new FileType(".txt");
+		public static final FileType ZIP = new FileType(".zip");
 
 		public boolean isDirectory() {
 			return extension == null;