diff --git a/lang/python/python3-host.mk b/lang/python/python3-host.mk
index 8a05c332cf..fdf6658fd8 100644
--- a/lang/python/python3-host.mk
+++ b/lang/python/python3-host.mk
@@ -12,6 +12,51 @@
 python3_mk_path:=$(dir $(lastword $(MAKEFILE_LIST)))
 include $(python3_mk_path)python3-version.mk
 
+# Unset environment variables
+
+# https://docs.python.org/3/using/cmdline.html#environment-variables
+unexport \
+	PYTHONHOME \
+	PYTHONPATH \
+	PYTHONSAFEPATH \
+	PYTHONPLATLIBDIR \
+	PYTHONSTARTUP \
+	PYTHONOPTIMIZE \
+	PYTHONBREAKPOINT \
+	PYTHONDEBUG \
+	PYTHONINSPECT \
+	PYTHONUNBUFFERED \
+	PYTHONVERBOSE \
+	PYTHONCASEOK \
+	PYTHONDONTWRITEBYTECODE \
+	PYTHONPYCACHEPREFIX \
+	PYTHONHASHSEED \
+	PYTHONINTMAXSTRDIGITS \
+	PYTHONIOENCODING \
+	PYTHONNOUSERSITE \
+	PYTHONUSERBASE \
+	PYTHONEXECUTABLE \
+	PYTHONWARNINGS \
+	PYTHONFAULTHANDLER \
+	PYTHONTRACEMALLOC \
+	PYTHONPROFILEIMPORTTIME \
+	PYTHONASYNCIODEBUG \
+	PYTHONMALLOC \
+	PYTHONMALLOCSTATS \
+	PYTHONLEGACYWINDOWSFSENCODING \
+	PYTHONLEGACYWINDOWSSTDIO \
+	PYTHONCOERCECLOCALE \
+	PYTHONDEVMODE \
+	PYTHONUTF8 \
+	PYTHONWARNDEFAULTENCODING \
+	PYTHONNODEBUGRANGES
+
+# https://docs.python.org/3/using/cmdline.html#debug-mode-variables
+unexport \
+	PYTHONTHREADDEBUG \
+	PYTHONDUMPREFS \
+	PYTHONDUMPREFSFILE
+
 HOST_PYTHON3_DIR:=$(STAGING_DIR_HOSTPKG)
 HOST_PYTHON3_INC_DIR:=$(HOST_PYTHON3_DIR)/include/python$(PYTHON3_VERSION)
 HOST_PYTHON3_LIB_DIR:=$(HOST_PYTHON3_DIR)/lib/python$(PYTHON3_VERSION)
@@ -31,10 +76,7 @@ HOST_PYTHON3_VARS = \
 	LDSHARED="$(HOSTCC) -shared" \
 	CFLAGS="$(HOST_CFLAGS)" \
 	CPPFLAGS="$(HOST_CPPFLAGS) -I$(HOST_PYTHON3_INC_DIR)" \
-	LDFLAGS="$(HOST_LDFLAGS) -lpython$(PYTHON3_VERSION) -Wl$(comma)-rpath$(comma)$(STAGING_DIR_HOSTPKG)/lib" \
-	PYTHONPATH="$(HOST_PYTHON3PATH)" \
-	PYTHONDONTWRITEBYTECODE=0 \
-	PYTHONOPTIMIZE=""
+	LDFLAGS="$(HOST_LDFLAGS) -lpython$(PYTHON3_VERSION) -Wl$(comma)-rpath$(comma)$(STAGING_DIR_HOSTPKG)/lib"
 
 # $(1) => directory of python script
 # $(2) => python script and its arguments
diff --git a/lang/python/python3-package.mk b/lang/python/python3-package.mk
index a24892ac57..8477d8c75d 100644
--- a/lang/python/python3-package.mk
+++ b/lang/python/python3-package.mk
@@ -42,7 +42,6 @@ PYTHON3_VARS = \
 	__PYVENV_LAUNCHER__="/usr/bin/$(PYTHON3)" \
 	PYTHONPATH="$(PYTHON3PATH)" \
 	PYTHONDONTWRITEBYTECODE=1 \
-	PYTHONOPTIMIZE="" \
 	_python_sysroot="$(STAGING_DIR)" \
 	_python_prefix="/usr" \
 	_python_exec_prefix="/usr"