diff --git a/src/main/onehot.cc b/src/main/onehot.cc
index 280db9c..d413b6e 100644
--- a/src/main/onehot.cc
+++ b/src/main/onehot.cc
@@ -76,7 +76,7 @@ void PrintUsage(std::ostream* stream) {
  *   - double-type one-hot vector
  *
  * @code{.sh}
- *   step -l 3 | x2x +di | onehot -l 3 | x2x +da
+ *   ramp -l 3 | x2x +di | onehot -l 3 | x2x +da
  *   # 1, 0, 0, 0, 1, 0, 0, 0, 1
  * @endcode
  *
diff --git a/tools/Makefile b/tools/Makefile
index a2d61ac..908886e 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -14,7 +14,7 @@
 # limitations under the License.                                           #
 # ------------------------------------------------------------------------ #
 
-PYTHON_VERSION     := 3.8
+PYTHON_VERSION     := 3.9
 SHELLCHECK_VERSION := 0.10.0
 SHFMT_VERSION      := 3.8.0
 JOBS               := 4