diff --git a/Dockerfile--alpine.tmpl b/Dockerfile--alpine.tmpl
index d8bbc73..651770f 100644
--- a/Dockerfile--alpine.tmpl
+++ b/Dockerfile--alpine.tmpl
@@ -13,6 +13,8 @@ RUN apk add --no-cache \
     sudo \
     git
 
+ENV PYTHON_BINARY=python3
+
 # --------------------------------------------- base2
 FROM base1 AS base2
 
diff --git a/Dockerfile--altlinux_10.tmpl b/Dockerfile--altlinux_10.tmpl
index 2e58975..afde673 100644
--- a/Dockerfile--altlinux_10.tmpl
+++ b/Dockerfile--altlinux_10.tmpl
@@ -23,7 +23,7 @@ RUN apt-get update && apt-get install -y \
     python3-dev \
     && apt-get clean
 
-ENV PYTHON_VERSION=3
+ENV PYTHON_BINARY=python3
 
 # --------------------------------------------- final
 FROM base2_with_python-${PYTHON_VERSION} AS final
@@ -90,7 +90,7 @@ if [ -n \"${TEST_CFG__REMOTE_SSH_KEY:-}\" ]; then \
 fi; \
 ls -la ./; \
 # AUTOMATIC TRANSFER: Save all TEST_CFG__xxx variables to a temporary file \
-(env | grep '^TEST_CFG__' | sed 's/^/export /' || echo '') > ./test_cfg_env.sh; \
+(env | grep -E '^(TEST_CFG__|PYTHON_BINARY)' | sed 's/^/export /' || echo '') > ./test_cfg_env.sh; \
 chown test:test ./test_cfg_env.sh; \
 cat ./test_cfg_env.sh; \
 # Run su -, pull in the file with variables and start the tests \
diff --git a/Dockerfile--altlinux_11.tmpl b/Dockerfile--altlinux_11.tmpl
index b91bca7..9d07970 100644
--- a/Dockerfile--altlinux_11.tmpl
+++ b/Dockerfile--altlinux_11.tmpl
@@ -24,7 +24,7 @@ RUN apt-get update && apt-get install -y \
     python3-dev \
     && apt-get clean
 
-ENV PYTHON_VERSION=3
+ENV PYTHON_BINARY=python3
 
 # --------------------------------------------- final
 FROM base2_with_python-${PYTHON_VERSION} AS final
@@ -91,7 +91,7 @@ if [ -n \"${TEST_CFG__REMOTE_SSH_KEY:-}\" ]; then \
 fi; \
 ls -la ./; \
 # AUTOMATIC TRANSFER: Save all TEST_CFG__xxx variables to a temporary file \
-(env | grep '^TEST_CFG__' | sed 's/^/export /' || echo '') > ./test_cfg_env.sh; \
+(env | grep -E '^(TEST_CFG__|PYTHON_BINARY)' | sed 's/^/export /' || echo '') > ./test_cfg_env.sh; \
 chown test:test ./test_cfg_env.sh; \
 cat ./test_cfg_env.sh; \
 # Run su -, pull in the file with variables and start the tests \
diff --git a/Dockerfile--astralinux_1_7.tmpl b/Dockerfile--astralinux_1_7.tmpl
index 0992a3e..0ddf6b8 100644
--- a/Dockerfile--astralinux_1_7.tmpl
+++ b/Dockerfile--astralinux_1_7.tmpl
@@ -24,7 +24,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     python3-venv \
     && rm -rf /var/lib/apt/lists/*
 
-ENV PYTHON_VERSION=3
+ENV PYTHON_BINARY=python3
 
 # --------------------------------------------- final
 FROM base2_with_python-${PYTHON_VERSION} AS final
diff --git a/Dockerfile--ubuntu_24_04.tmpl b/Dockerfile--ubuntu_24_04.tmpl
index 1f46d01..ad3f5e7 100644
--- a/Dockerfile--ubuntu_24_04.tmpl
+++ b/Dockerfile--ubuntu_24_04.tmpl
@@ -27,7 +27,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     python3-venv \
     && rm -rf /var/lib/apt/lists/*
 
-ENV PYTHON_VERSION=3
+ENV PYTHON_BINARY=python3
 
 # --------------------------------------------- final
 FROM base2_with_python-${PYTHON_VERSION} AS final
diff --git a/run_tests3.sh b/run_tests3.sh
index 339340e..3a9757d 100755
--- a/run_tests3.sh
+++ b/run_tests3.sh
@@ -4,15 +4,15 @@ set -eux
 # prepare python environment
 VENV_PATH="/tmp/testgres_venv"
 rm -rf $VENV_PATH
-python3 -m venv "${VENV_PATH}"
+${PYTHON_BINARY} -m venv "${VENV_PATH}"
 export VIRTUAL_ENV_DISABLE_PROMPT=1
 source "${VENV_PATH}/bin/activate"
 pip install --upgrade pip setuptools wheel
-python3 -m pip install -r tests/requirements.txt
+${PYTHON_BINARY} -m pip install -r tests/requirements.txt
 
 export -p
 
 # run builtin tests
-python3 -m pytest -l -vvv -n 4
+${PYTHON_BINARY} -m pytest -l -vvv -n 4
 
 set +eux