diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index 4a71a57ec0d..2b40ada195a 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -146,9 +146,15 @@ dircheck(fileio* self, PyObject *nameobj)
 {
 #if defined(HAVE_FSTAT) && defined(S_IFDIR) && defined(EISDIR)
     struct stat buf;
+    int res;
     if (self->fd < 0)
         return 0;
-    if (fstat(self->fd, &buf) == 0 && S_ISDIR(buf.st_mode)) {
+
+    Py_BEGIN_ALLOW_THREADS
+    res = fstat(self->fd, &buf);
+    Py_END_ALLOW_THREADS
+
+    if (res == 0 && S_ISDIR(buf.st_mode)) {
         errno = EISDIR;
         PyErr_SetFromErrnoWithFilenameObject(PyExc_IOError, nameobj);
         return -1;
@@ -162,17 +168,34 @@ check_fd(int fd)
 {
 #if defined(HAVE_FSTAT)
     struct stat buf;
-    if (!_PyVerify_fd(fd) || (fstat(fd, &buf) < 0 && errno == EBADF)) {
-        PyObject *exc;
-        char *msg = strerror(EBADF);
-        exc = PyObject_CallFunction(PyExc_OSError, "(is)",
-                                    EBADF, msg);
-        PyErr_SetObject(PyExc_OSError, exc);
-        Py_XDECREF(exc);
-        return -1;
+    int res;
+    PyObject *exc;
+    char *msg;
+
+    if (!_PyVerify_fd(fd)) {
+        goto badfd;
     }
-#endif
+
+    Py_BEGIN_ALLOW_THREADS
+    res = fstat(fd, &buf);
+    Py_END_ALLOW_THREADS
+
+    if (res < 0 && errno == EBADF) {
+        goto badfd;
+    }
+
     return 0;
+
+badfd:
+    msg = strerror(EBADF);
+    exc = PyObject_CallFunction(PyExc_OSError, "(is)",
+                                EBADF, msg);
+    PyErr_SetObject(PyExc_OSError, exc);
+    Py_XDECREF(exc);
+    return -1;
+#else
+    return 0;
+#endif
 }
 
 
@@ -519,9 +542,19 @@ new_buffersize(fileio *self, size_t currentsize)
 #ifdef HAVE_FSTAT
     off_t pos, end;
     struct stat st;
-    if (fstat(self->fd, &st) == 0) {
+    int res;
+
+    Py_BEGIN_ALLOW_THREADS
+    res = fstat(self->fd, &st);
+    Py_END_ALLOW_THREADS
+
+    if (res == 0) {
         end = st.st_size;
+
+        Py_BEGIN_ALLOW_THREADS
         pos = lseek(self->fd, 0L, SEEK_CUR);
+        Py_END_ALLOW_THREADS
+
         /* Files claiming a size smaller than SMALLCHUNK may
            actually be streaming pseudo-files. In this case, we
            apply the more aggressive algorithm below.
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index 2f63c374d1e..8d1c5812f0d 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -121,10 +121,15 @@ dircheck(PyFileObject* f)
 {
 #if defined(HAVE_FSTAT) && defined(S_IFDIR) && defined(EISDIR)
     struct stat buf;
+    int res;
     if (f->f_fp == NULL)
         return f;
-    if (fstat(fileno(f->f_fp), &buf) == 0 &&
-        S_ISDIR(buf.st_mode)) {
+
+    Py_BEGIN_ALLOW_THREADS
+    res = fstat(fileno(f->f_fp), &buf);
+    Py_END_ALLOW_THREADS
+
+    if (res == 0 && S_ISDIR(buf.st_mode)) {
         char *msg = strerror(EISDIR);
         PyObject *exc = PyObject_CallFunction(PyExc_IOError, "(isO)",
                                               EISDIR, msg, f->f_name);
@@ -1010,7 +1015,13 @@ new_buffersize(PyFileObject *f, size_t currentsize)
 #ifdef HAVE_FSTAT
     off_t pos, end;
     struct stat st;
-    if (fstat(fileno(f->f_fp), &st) == 0) {
+    int res;
+
+    Py_BEGIN_ALLOW_THREADS
+    res = fstat(fileno(f->f_fp), &st);
+    Py_END_ALLOW_THREADS
+
+    if (res == 0) {
         end = st.st_size;
         /* The following is not a bug: we really need to call lseek()
            *and* ftell().  The reason is that some stdio libraries
@@ -1021,7 +1032,11 @@ new_buffersize(PyFileObject *f, size_t currentsize)
            works.  We can't use the lseek() value either, because we
            need to take the amount of buffered data into account.
            (Yet another reason why stdio stinks. :-) */
+
+        Py_BEGIN_ALLOW_THREADS
         pos = lseek(fileno(f->f_fp), 0L, SEEK_CUR);
+        Py_END_ALLOW_THREADS
+
         if (pos >= 0) {
             pos = ftell(f->f_fp);
         }