diff --git a/tox.ini b/tox.ini
index 0e156d63b..bf646242b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -32,7 +32,7 @@ download = true
 commands =
     pytest --cov=scrapy --cov-report=xml --cov-report= {posargs:--durations=10 docs scrapy tests}
 install_command =
-    pip install -U -ctests/upper-constraints.txt {opts} {packages}
+    python -I -m pip install -ctests/upper-constraints.txt {opts} {packages}
 
 [testenv:typing]
 basepython = python3
@@ -107,7 +107,7 @@ deps =
 setenv =
     _SCRAPY_PINNED=true
 install_command =
-    pip install -U {opts} {packages}
+    python -I -m pip install {opts} {packages}
 
 [testenv:pinned]
 deps =