diff --git a/python/Makefile b/python/Makefile
index 0d98f9019926..76dfdcf01302 100644
--- a/python/Makefile
+++ b/python/Makefile
@@ -1,6 +1,6 @@
 export CC  = gcc
 export CXX = g++
-export CFLAGS = -Wall -O3 -msse2  -Wno-unknown-pragmas # -fopenmp
+export CFLAGS = -Wall -O3 -msse2  -Wno-unknown-pragmas  -fopenmp
 
 # specify tensor path
 SLIB = libxgboostpy.so