diff --git a/src/python-lz4.c b/src/python-lz4.c
index 45fe995..9290918 100644
--- a/src/python-lz4.c
+++ b/src/python-lz4.c
@@ -73,7 +73,10 @@ static PyObject *compress_with(compressor compress, PyObject *self, PyObject *ar
     dest = PyBytes_AS_STRING(result);
     store_le32(dest, source_size);
     if (source_size > 0) {
-        int osize = compress(source, dest + hdr_size, source_size);
+        int osize = -1;
+        Py_BEGIN_ALLOW_THREADS
+        osize = compress(source, dest + hdr_size, source_size);
+        Py_END_ALLOW_THREADS
         int actual_size = hdr_size + osize;
         /* Resizes are expensive; tolerate some slop to avoid. */
         if (actual_size < (dest_size / 4) * 3) {
@@ -115,7 +118,10 @@ static PyObject *py_lz4_uncompress(PyObject *self, PyObject *args) {
     result = PyBytes_FromStringAndSize(NULL, dest_size);
     if (result != NULL && dest_size > 0) {
         char *dest = PyBytes_AS_STRING(result);
-        int osize = LZ4_decompress_safe(source + hdr_size, dest, source_size - hdr_size, dest_size);
+        int osize = -1;
+        Py_BEGIN_ALLOW_THREADS
+        osize = LZ4_decompress_safe(source + hdr_size, dest, source_size - hdr_size, dest_size);
+        Py_END_ALLOW_THREADS
         if (osize < 0) {
             PyErr_Format(PyExc_ValueError, "corrupt input at byte %d", -osize);
             Py_CLEAR(result);
diff --git a/tests/test.py b/tests/test.py
index 9469a03..5b099bb 100644
--- a/tests/test.py
+++ b/tests/test.py
@@ -2,6 +2,7 @@
 import sys
 
 
+from multiprocessing.pool import ThreadPool
 import unittest
 import os
 
@@ -11,6 +12,17 @@ def test_random(self):
       DATA = os.urandom(128 * 1024)  # Read 128kb
       self.assertEqual(DATA, lz4.loads(lz4.dumps(DATA)))
 
+    def test_threads(self):
+        data = [os.urandom(128 * 1024) for i in range(100)]
+        def roundtrip(x):
+            return lz4.loads(lz4.dumps(x))
+
+        pool = ThreadPool(8)
+        out = pool.map(roundtrip, data)
+        assert data == out
+        pool.close()
+
+
 if __name__ == '__main__':
     unittest.main()