diff --git a/com.avaloq.tools.ddk.xtext/src/com/avaloq/tools/ddk/xtext/resource/persistence/DirectLinkingResourceStorageLoadable.java b/com.avaloq.tools.ddk.xtext/src/com/avaloq/tools/ddk/xtext/resource/persistence/DirectLinkingResourceStorageLoadable.java
index fe43764b2..e56a35f71 100644
--- a/com.avaloq.tools.ddk.xtext/src/com/avaloq/tools/ddk/xtext/resource/persistence/DirectLinkingResourceStorageLoadable.java
+++ b/com.avaloq.tools.ddk.xtext/src/com/avaloq/tools/ddk/xtext/resource/persistence/DirectLinkingResourceStorageLoadable.java
@@ -11,7 +11,6 @@
 
 package com.avaloq.tools.ddk.xtext.resource.persistence;
 
-import java.io.BufferedInputStream;
 import java.io.DataInputStream;
 import java.io.IOException;
 import java.io.InputStream;
@@ -150,7 +149,7 @@ protected void loadEntries(final StorageAwareResource resource, final ZipInputSt
       // fall through
     case LOAD:
       positioner.position(Constituent.CONTENT);
-      readContents(resource, new BufferedInputStream(zipIn));
+      readContents(resource, new NonLockingBufferInputStream(zipIn));
       break;
     }
 
@@ -163,7 +162,7 @@ protected void loadEntries(final StorageAwareResource resource, final ZipInputSt
       break;
     default:
       positioner.position(Constituent.ASSOCIATIONS);
-      readAssociationsAdapter(resource, new BufferedInputStream(zipIn));
+      readAssociationsAdapter(resource, new NonLockingBufferInputStream(zipIn));
       break;
     }
 
@@ -194,7 +193,7 @@ protected void loadEntries(final StorageAwareResource resource, final ZipInputSt
         break;
       case LOAD:
         positioner.position(Constituent.NODE_MODEL);
-        readNodeModel(resource, new BufferedInputStream(zipIn), content);
+        readNodeModel(resource, new NonLockingBufferInputStream(zipIn), content);
         break;
       }
     }
diff --git a/com.avaloq.tools.ddk.xtext/src/com/avaloq/tools/ddk/xtext/resource/persistence/NonLockingBufferInputStream.java b/com.avaloq.tools.ddk.xtext/src/com/avaloq/tools/ddk/xtext/resource/persistence/NonLockingBufferInputStream.java
new file mode 100644
index 000000000..0c2c0876b
--- /dev/null
+++ b/com.avaloq.tools.ddk.xtext/src/com/avaloq/tools/ddk/xtext/resource/persistence/NonLockingBufferInputStream.java
@@ -0,0 +1,288 @@
+/*******************************************************************************
+ * Copyright (c) 2024 Avaloq Group AG and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     Avaloq Group AG - initial API and implementation
+ *******************************************************************************/
+package com.avaloq.tools.ddk.xtext.resource.persistence;
+
+import java.io.FilterInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.Arrays;
+import java.util.Objects;
+
+
+/**
+ * Like {@code BufferedInputStream} without supporting concurrency.
+ */
+@SuppressWarnings("nls")
+public class NonLockingBufferInputStream extends FilterInputStream {
+
+  private static final int DEFAULT_BUFFER_SIZE = 8192;
+  private static final byte[] EMPTY = new byte[0];
+  private final int initialSize;
+
+  private byte[] buf;
+  private int count;
+  private int pos;
+  private int markpos = -1;
+  private int marklimit;
+
+  private byte[] getBufIfOpen(final boolean allocateIfEmpty) throws IOException {
+    if (allocateIfEmpty && buf == EMPTY) {
+      buf = new byte[initialSize];
+    }
+    return buf;
+  }
+
+  private byte[] getBufIfOpen() throws IOException {
+    return getBufIfOpen(true);
+  }
+
+  private void ensureOpen() throws IOException {
+    if (buf == null) {
+      throw new IOException("Stream closed");
+    }
+  }
+
+  /**
+   * Creates a {@code NonLockingBufferInputStream}.
+   *
+   * @param in
+   *          the underlying input stream.
+   */
+  public NonLockingBufferInputStream(final InputStream in) {
+    this(in, DEFAULT_BUFFER_SIZE);
+  }
+
+  /**
+   * Creates a {@code NonLockingBufferInputStream}
+   * with the specified buffer size.
+   *
+   * @param in
+   *          the underlying input stream.
+   * @param size
+   *          the buffer size.
+   * @throws IllegalArgumentException
+   *           if {@code size <= 0}.
+   */
+  public NonLockingBufferInputStream(final InputStream in, final int size) {
+    super(in);
+    if (size <= 0) {
+      throw new IllegalArgumentException("Buffer size <= 0");
+    }
+    initialSize = size;
+    buf = new byte[size];
+  }
+
+  private static final int SOFT_MAX_ARRAY_LENGTH = Integer.MAX_VALUE - 8;
+
+  private static int newLength(final int oldLength, final int minGrowth, final int prefGrowth) {
+    int prefLength = oldLength + Math.max(minGrowth, prefGrowth); // might overflow
+    if (0 < prefLength && prefLength <= SOFT_MAX_ARRAY_LENGTH) {
+      return prefLength;
+    } else {
+      return hugeLength(oldLength, minGrowth);
+    }
+  }
+
+  private static int hugeLength(final int oldLength, final int minGrowth) {
+    int minLength = oldLength + minGrowth;
+    if (minLength < 0) { // overflow
+      throw new OutOfMemoryError("Required array length " + oldLength + " + " + minGrowth + " is too large");
+    } else if (minLength <= SOFT_MAX_ARRAY_LENGTH) {
+      return SOFT_MAX_ARRAY_LENGTH;
+    } else {
+      return minLength;
+    }
+  }
+
+  private void fill() throws IOException {
+    byte[] buffer = getBufIfOpen();
+    if (markpos == -1) {
+      pos = 0; /* no mark: throw away the buffer */
+    } else if (pos >= buffer.length) { /* no room left in buffer */
+      if (markpos > 0) { /* can throw away early part of the buffer */
+        int sz = pos - markpos;
+        System.arraycopy(buffer, markpos, buffer, 0, sz);
+        pos = sz;
+        markpos = 0;
+      } else if (buffer.length >= marklimit) {
+        markpos = -1; /* buffer got too big, invalidate mark */
+        pos = 0; /* drop buffer contents */
+      } else { /* grow buffer */
+        int nsz = newLength(pos, 1, pos);
+        if (nsz > marklimit) {
+          nsz = marklimit;
+        }
+        byte[] nbuf = new byte[nsz];
+        System.arraycopy(buffer, 0, nbuf, 0, pos);
+        buffer = nbuf;
+      }
+    }
+    count = pos;
+    int n = in.read(buffer, pos, buffer.length - pos);
+    if (n > 0) {
+      count = n + pos;
+    }
+  }
+
+  @Override
+  @SuppressWarnings("checkstyle:MagicNumberCheck")
+  public int read() throws IOException {
+    if (pos >= count) {
+      fill();
+      if (pos >= count) {
+        return -1;
+      }
+    }
+    return getBufIfOpen()[pos++] & 0xff;
+  }
+
+  private int read1(final byte[] b, final int off, final int len) throws IOException {
+    int avail = count - pos;
+    if (avail <= 0) {
+      /*
+       * If the requested length is at least as large as the buffer, and
+       * if there is no mark/reset activity, do not bother to copy the
+       * bytes into the local buffer. In this way buffered streams will
+       * cascade harmlessly.
+       */
+      int size = Math.max(getBufIfOpen(false).length, initialSize);
+      if (len >= size && markpos == -1) {
+        return in.read(b, off, len);
+      }
+      fill();
+      avail = count - pos;
+      if (avail <= 0) {
+        return -1;
+      }
+    }
+    int cnt = (avail < len) ? avail : len;
+    System.arraycopy(getBufIfOpen(), pos, b, off, cnt);
+    pos += cnt;
+    return cnt;
+  }
+
+  @Override
+  public int read(final byte[] b, final int off, final int len) throws IOException {
+    ensureOpen();
+    if ((off | len | (off + len) | (b.length - (off + len))) < 0) {
+      throw new IndexOutOfBoundsException();
+    } else if (len == 0) {
+      return 0;
+    }
+
+    int n = 0;
+    for (;;) {
+      int nread = read1(b, off + n, len - n);
+      if (nread <= 0) {
+        return (n == 0) ? nread : n;
+      }
+      n += nread;
+      if (n >= len) {
+        return n;
+      }
+      // if not closed but no bytes available, return
+      InputStream input = in;
+      if (input != null && input.available() <= 0) {
+        return n;
+      }
+    }
+  }
+
+  @Override
+  public long skip(final long n) throws IOException {
+    ensureOpen();
+    if (n <= 0) {
+      return 0;
+    }
+    long avail = count - pos;
+
+    if (avail <= 0) {
+      // If no mark position set then don't keep in buffer
+      if (markpos == -1) {
+        return in.skip(n);
+      }
+
+      // Fill in buffer to save bytes for reset
+      fill();
+      avail = count - pos;
+      if (avail <= 0) {
+        return 0;
+      }
+    }
+
+    long skipped = (avail < n) ? avail : n;
+    pos += (int) skipped;
+    return skipped;
+  }
+
+  @Override
+  public int available() throws IOException {
+    int n = count - pos;
+    int avail = in.available();
+    return n > (Integer.MAX_VALUE - avail) ? Integer.MAX_VALUE : n + avail;
+  }
+
+  @Override
+  public void mark(final int readlimit) {
+    marklimit = readlimit;
+    markpos = pos;
+  }
+
+  @Override
+  public void reset() throws IOException {
+    ensureOpen();
+    if (markpos < 0) {
+      throw new IOException("Resetting to invalid mark");
+    }
+    pos = markpos;
+  }
+
+  @Override
+  public boolean markSupported() {
+    return true;
+  }
+
+  @Override
+  public void close() throws IOException {
+    while (buf != null) {
+      buf = null;
+      InputStream input = in;
+      in = null;
+      if (input != null) {
+        input.close();
+      }
+      return;
+    }
+  }
+
+  @Override
+  public long transferTo(final OutputStream out) throws IOException {
+    Objects.requireNonNull(out, "out");
+    if (markpos == -1) {
+      int avail = count - pos;
+      if (avail > 0) {
+        // Prevent poisoning and leaking of buf
+        byte[] buffer = Arrays.copyOfRange(getBufIfOpen(), pos, count);
+        out.write(buffer);
+        pos = count;
+      }
+      try {
+        return Math.addExact(avail, in.transferTo(out));
+      } catch (ArithmeticException ignore) {
+        return Long.MAX_VALUE;
+      }
+    } else {
+      return super.transferTo(out);
+    }
+  }
+
+}