diff --git a/src/main/java/org/cryptomator/frontend/fuse/OpenFile.java b/src/main/java/org/cryptomator/frontend/fuse/OpenFile.java
index 5fc4dd9..a25ee55 100644
--- a/src/main/java/org/cryptomator/frontend/fuse/OpenFile.java
+++ b/src/main/java/org/cryptomator/frontend/fuse/OpenFile.java
@@ -19,11 +19,14 @@ public class OpenFile implements Closeable {
 	private final Path path;
 	private final FileChannel channel;
 
+	private volatile boolean writeCalled;
+
 	private OpenFile(Path path, FileChannel channel) {
 		this.path = path;
 		this.channel = channel;
+		this.writeCalled = false;
 	}
-	
+
 	static OpenFile create(Path path, Set<? extends OpenOption> options, FileAttribute<?>... attrs) throws IOException {
 		FileChannel ch = FileChannel.open(path, options, attrs);
 		return new OpenFile(path, ch);
@@ -69,6 +72,7 @@ public int read(ByteBuffer buf, long num, long offset) throws IOException {
 	 * @throws IOException If an exception occurs during write.
 	 */
 	public int write(ByteBuffer buf, long num, long offset) throws IOException {
+		writeCalled = true;
 		if (num > Integer.MAX_VALUE) {
 			throw new IOException("Requested too many bytes");
 		}
@@ -80,6 +84,15 @@ public int write(ByteBuffer buf, long num, long offset) throws IOException {
 		return written;
 	}
 
+	/**
+	 * Tests, if the write method of this open file was called at least once.
+	 *
+	 * @return {@code true} if {@link OpenFile#write(ByteBuffer, long, long)} was called on this object, otherwise {@code false}
+	 */
+	public boolean isWrittenTo() {
+		return writeCalled;
+	}
+
 	@Override
 	public void close() throws IOException {
 		channel.close();
diff --git a/src/main/java/org/cryptomator/frontend/fuse/OpenFileFactory.java b/src/main/java/org/cryptomator/frontend/fuse/OpenFileFactory.java
index f1471cb..f7b6cf1 100644
--- a/src/main/java/org/cryptomator/frontend/fuse/OpenFileFactory.java
+++ b/src/main/java/org/cryptomator/frontend/fuse/OpenFileFactory.java
@@ -67,8 +67,14 @@ public void close(long fileHandle) throws ClosedChannelException, IOException {
 		}
 	}
 
-	public int getOpenFileCount(){
-		return openFiles.size();
+	/**
+	 * Tests, if there exists {@link OpenFile}s, which has been written to.
+	 * The check performed in this method is not atomic and therefore requires external synchronization.
+	 *
+	 * @return {@code true} if and only if at least one {@link OpenFile} exists, where {@link OpenFile#isWrittenTo()} returns {@code true}. Otherwise {@code false}.
+	 */
+	public boolean hasWrittenToOpenFiles(){
+		return openFiles.entrySet().stream().anyMatch(entry -> entry.getValue().isWrittenTo());
 	}
 
 	/**
diff --git a/src/main/java/org/cryptomator/frontend/fuse/ReadOnlyAdapter.java b/src/main/java/org/cryptomator/frontend/fuse/ReadOnlyAdapter.java
index a4c8064..ff9fcbd 100644
--- a/src/main/java/org/cryptomator/frontend/fuse/ReadOnlyAdapter.java
+++ b/src/main/java/org/cryptomator/frontend/fuse/ReadOnlyAdapter.java
@@ -48,7 +48,6 @@ public sealed class ReadOnlyAdapter implements FuseNioAdapter permits ReadWriteA
 	private final ReadOnlyDirectoryHandler dirHandler;
 	private final ReadOnlyFileHandler fileHandler;
 	private final ReadOnlyLinkHandler linkHandler;
-	private final BooleanSupplier hasOpenFiles;
 
 	protected ReadOnlyAdapter(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder, FileStore fileStore, OpenFileFactory openFiles, ReadOnlyDirectoryHandler dirHandler, ReadOnlyFileHandler fileHandler) {
 		this.errno = errno;
@@ -61,7 +60,6 @@ protected ReadOnlyAdapter(Errno errno, Path root, int maxFileNameLength, FileNam
 		this.dirHandler = dirHandler;
 		this.fileHandler = fileHandler;
 		this.linkHandler = new ReadOnlyLinkHandler(fileNameTranscoder);
-		this.hasOpenFiles = () -> openFiles.getOpenFileCount() != 0;
 	}
 
 	public static ReadOnlyAdapter create(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder) {
@@ -305,7 +303,7 @@ public void destroy() {
 	@Override
 	public boolean isInUse() {
 		try (PathLock pLock = lockManager.tryLockForWriting("/")) {
-			return hasOpenFiles.getAsBoolean();
+			return openFiles.hasWrittenToOpenFiles();
 		} catch (AlreadyLockedException e) {
 			return true;
 		}
@@ -320,7 +318,7 @@ public void close() throws IOException {
 	 * Attempts to get a specific error code that best describes the given exception.
 	 * As a side effect this logs the error.
 	 *
-	 * @param e An exception
+	 * @param e      An exception
 	 * @param opDesc A human-friendly string describing what operation was attempted (for logging purposes)
 	 * @return A specific error code or -EIO.
 	 */
@@ -331,8 +329,8 @@ protected int getErrorCodeForGenericFileSystemException(FileSystemException e, S
 //			LOG.warn("{} {} failed, name too long.", opDesc);
 //			return -ErrorCodes.ENAMETOOLONG();
 //		} else {
-			LOG.error(opDesc + " failed.", e);
-			return -errno.eio();
+		LOG.error(opDesc + " failed.", e);
+		return -errno.eio();
 //		}
 	}
 }