diff --git a/src/main/java/net/fabricmc/tinyremapper/TinyRemapper.java b/src/main/java/net/fabricmc/tinyremapper/TinyRemapper.java
index a7f0c090..b35d53e5 100644
--- a/src/main/java/net/fabricmc/tinyremapper/TinyRemapper.java
+++ b/src/main/java/net/fabricmc/tinyremapper/TinyRemapper.java
@@ -475,17 +475,14 @@ private List<CompletableFuture<List<ClassInstance>>> read(final Path file, boole
 			final boolean saveData, final List<FileSystemReference> fsToClose) throws IOException {
 		List<CompletableFuture<List<ClassInstance>>> ret = new ArrayList<>();
 
-		Files.walkFileTree(file, new SimpleFileVisitor<Path>() {
-			@Override
-			public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
-				String name = file.getFileName().toString();
-
-				if (name.endsWith(".jar")
-						|| name.endsWith(".zip")
-						|| name.endsWith(".class")) {
-					ret.add(CompletableFuture.supplyAsync(new Supplier<List<ClassInstance>>() {
-						@Override
-						public List<ClassInstance> get() {
+		if (Files.isDirectory(file)) {
+			Files.walkFileTree(file, new SimpleFileVisitor<Path>() {
+				@Override
+				public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
+					String name = file.getFileName().toString();
+
+					if (name.endsWith(".class")) {
+						ret.add(CompletableFuture.supplyAsync(() -> {
 							try {
 								return readFile(file, isInput, tags, srcPath, fsToClose);
 							} catch (URISyntaxException e) {
@@ -493,13 +490,24 @@ public List<ClassInstance> get() {
 							} catch (IOException | ZipError e) {
 								throw new RuntimeException("Error reading file "+file, e);
 							}
-						}
-					}, threadPool));
+						}, threadPool));
+					}
+
+					return FileVisitResult.CONTINUE;
 				}
+			});
+		} else {
+			ret.add(CompletableFuture.supplyAsync(() -> {
+				try {
+					return readFile(file, isInput, tags, srcPath, fsToClose);
+				} catch (URISyntaxException e) {
+					throw new RuntimeException(e);
+				} catch (IOException | ZipError e) {
+					throw new RuntimeException("Error reading file "+file, e);
+				}
+			}));
+		}
 
-				return FileVisitResult.CONTINUE;
-			}
-		});
 
 		return ret;
 	}