diff --git a/fix-crash-on-parallel-build.patch b/fix-crash-on-parallel-build.patch
new file mode 100644
index 0000000..9bf01c7
--- /dev/null
+++ b/fix-crash-on-parallel-build.patch
@@ -0,0 +1,12 @@
+diff --git a/sphinx/util/parallel.py b/sphinx/util/parallel.py
+index ce51ac0..64f9bc1 100644
+--- a/sphinx/util/parallel.py
++++ b/sphinx/util/parallel.py
+@@ -100,6 +100,7 @@ class ParallelTasks(object):
+                     raise SphinxParallelError(*result)
+                 self._result_funcs.pop(tid)(self._args.pop(tid), result)
+                 self._procs[tid].join()
++                self._precvs.pop(tid)
+                 self._pworking -= 1
+                 break
+         else:
diff --git a/python-sphinx.spec b/python-sphinx.spec
index e18ed13..18972fd 100644
--- a/python-sphinx.spec
+++ b/python-sphinx.spec
@@ -15,7 +15,7 @@
 
 Name:       python-sphinx
 Version:    1.5.2
-Release:    3%{?dist}
+Release:    4%{?dist}
 Epoch:      1
 Summary:    Python documentation generator
 
@@ -37,6 +37,13 @@ Source5:    README.fedora
 # python-sphinx execuitables is default
 Source6:    default-sphinx-command.in
 
+# Backport of a bugfix from the 1.6 upstream branch of sphinx
+# to address a crash with parallel building.
+# https://bugzilla.redhat.com/show_bug.cgi?id=1494276
+# Upstream commit:
+# https://github.com/sphinx-doc/sphinx/pull/4039/commits/0cb57f19a099be2809a8fb5dc9274f7411e1caac
+Patch0: fix-crash-on-parallel-build.patch
+
 BuildArch:     noarch
 BuildRequires: python2-devel >= 2.4
 BuildRequires: python2-babel
@@ -583,6 +590,9 @@ popd
 
 
 %changelog
+* Fri Sep 22 2017 Charalampos Stratakis <cstratak@redhat.com> - 1:1.5.2-4
+- Fix a crash on parallel build.
+
 * Wed Sep 20 2017 Charalampos Stratakis <cstratak@redhat.com> - 1:1.5.2-3
 - Provide the epoch tag in order to downgrade at Fedora 26