diff --git a/documentation/conf.py b/documentation/conf.py
index cf0da0d651baeb87258563c2c1348375ddc89f52..f98ba70eb19e055e9d8efd9db7fd6094b427e519 100644
--- a/documentation/conf.py
+++ b/documentation/conf.py
@@ -17,7 +17,7 @@ read_the_docs_build = os.environ.get('READTHEDOCS', None) == 'True'
 
 if read_the_docs_build:
     configureDoxyfile("Doxyfile.in", "Doxyfile", "../", "_build/workdir/doxygen")
-    s = subprocess.check_output(["git rev-parse", "--abbrev-ref HEAD"])
+    s = subprocess.check_output(["git", "rev-parse --abbrev-ref HEAD"])
     print("s = " + s)
     subprocess.call('mkdir -p _build/workdir/doxygen; doxygen Doxyfile', shell=True)
     html_extra_path = ['_build/workdir/']