diff --git a/documentation/conf.py b/documentation/conf.py
index 96f3ae8a5c0ef8a115cddd2073e99eb381782f1f..f27bbead4a6e3ab75fcc5a792ea725320b602f25 100644
--- a/documentation/conf.py
+++ b/documentation/conf.py
@@ -18,7 +18,7 @@ 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'])
-    print("s = " + s)
+    print("s = " + s.decode())
     subprocess.call('mkdir -p _build/workdir/doxygen; doxygen Doxyfile', shell=True)
     html_extra_path = ['_build/workdir/']