diff --git a/config/ax_python_devel.m4 b/config/ax_python_devel.m4
index fcf73dc20..7adcf01a0 100644
--- a/config/ax_python_devel.m4
+++ b/config/ax_python_devel.m4
@@ -224,7 +224,7 @@ EOD`
 				ac_python_version=$PYTHON_VERSION
 			else
 				ac_python_version=`$PYTHON -c "import sys; \
-					print (sys.version[[:3]])"`
+					print ('.'.join(sys.version.split('.')[[:2]]))"`
 			fi
 		fi