diff --git a/makefiles/Makefile.cpp.mk b/makefiles/Makefile.cpp.mk
index 4bf217c538..effbe343fc 100644
--- a/makefiles/Makefile.cpp.mk
+++ b/makefiles/Makefile.cpp.mk
@@ -43,6 +43,7 @@ USE_XPRESS ?= OFF
 
 USE_DOTNET_CORE_31 ?= ON
 USE_DOTNET_6 ?= ON
+BUILD_VENV ?= ON
 JOBS ?= 4
 
 # Main targets.
@@ -74,6 +75,7 @@ third_party:
  -DUSE_XPRESS=$(USE_XPRESS) \
  -DUSE_DOTNET_CORE_31=$(USE_DOTNET_CORE_31) \
  -DUSE_DOTNET_6=$(USE_DOTNET_6) \
+ -DBUILD_VENV=$(BUILD_VENV) \
  -DCMAKE_BUILD_TYPE=$(BUILD_TYPE) \
  -DCMAKE_INSTALL_PREFIX=$(INSTALL_DIR) \
  $(CMAKE_ARGS) \
diff --git a/makefiles/Makefile.python.mk b/makefiles/Makefile.python.mk
index c674fc82cd..729b4b365a 100644
--- a/makefiles/Makefile.python.mk
+++ b/makefiles/Makefile.python.mk
@@ -50,7 +50,7 @@ PYTHON_BUILD_PATH := $(BUILD_DIR)$Spython
 
 # OR Tools unique library.
 python:
-	$(MAKE) third_party BUILD_PYTHON=ON
+	$(MAKE) third_party BUILD_PYTHON=ON BUILD_VENV=ON
 	cmake --build $(BUILD_DIR) --target install --config $(BUILD_TYPE) -j $(JOBS) -v
 
 ifeq ($(PLATFORM),WIN64)