diff --git a/CHANGES b/CHANGES
index 3b0bbe0..d5b66df 100644
--- a/CHANGES
+++ b/CHANGES
@@ -9,6 +9,8 @@ Lib/
 Modules/
 * Fixed checking for empty server error message
   (thanks to Bradley Baetz)
+* Fixed releasing GIL when calling ldap_start_tls_s()
+  (thanks to Lars Munch)
 
 ----------------------------------------------------------------
 Released 2.4.28 2016-11-17
@@ -1308,4 +1310,4 @@ Released 2.0.0pre02 2002-02-01
 ----------------------------------------------------------------
 Released 1.10alpha3 2000-09-19
 
-$Id: CHANGES,v 1.400 2017/01/06 15:11:14 stroeder Exp $
+$Id: CHANGES,v 1.401 2017/01/25 19:41:31 stroeder Exp $
diff --git a/Modules/LDAPObject.c b/Modules/LDAPObject.c
index 10f166a..a0ab8c6 100644
--- a/Modules/LDAPObject.c
+++ b/Modules/LDAPObject.c
@@ -1,5 +1,5 @@
 /* See http://www.python-ldap.org/ for details.
- * $Id: LDAPObject.c,v 1.94 2016/01/26 11:01:08 stroeder Exp $ */
+ * $Id: LDAPObject.c,v 1.95 2017/01/25 19:41:31 stroeder Exp $ */
 
 #include "common.h"
 #include "patchlevel.h"
@@ -1213,14 +1213,16 @@ l_ldap_whoami_s( LDAPObject* self, PyObject* args )
 static PyObject*
 l_ldap_start_tls_s( LDAPObject* self, PyObject* args )
 {
-    int result;
+    int ldaperror;
 
     if (!PyArg_ParseTuple( args, "" )) return NULL;
     if (not_valid(self)) return NULL;
 
-    result = ldap_start_tls_s( self->ldap, NULL, NULL );
-    if ( result != LDAP_SUCCESS ){
-        ldap_set_option(self->ldap, LDAP_OPT_ERROR_NUMBER, &result);
+    LDAP_BEGIN_ALLOW_THREADS( self );
+    ldaperror = ldap_start_tls_s( self->ldap, NULL, NULL );
+    LDAP_END_ALLOW_THREADS( self );
+    if ( ldaperror != LDAP_SUCCESS ){
+        ldap_set_option(self->ldap, LDAP_OPT_ERROR_NUMBER, &ldaperror);
         return LDAPerror( self->ldap, "ldap_start_tls_s" );
     }