diff --git a/scripts/install b/scripts/install
index 55cd59e..4aa2283 100644
--- a/scripts/install
+++ b/scripts/install
@@ -128,7 +128,7 @@ virtualenv --python=python3 --system-site-packages "${final_path}/venv"
 	set -o nounset
 
 	pip install --upgrade pip
-	pip install weboob html2text simplejson BeautifulSoup4 PyExecJS pdfminer.six
+	pip install weboob html2text simplejson BeautifulSoup4 PyExecJS pdfminer.six --ignore-installed
 )
 
 #=================================================
diff --git a/scripts/upgrade b/scripts/upgrade
index 4f65e4a..7dd6117 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -139,7 +139,7 @@ virtualenv --python=python3 --system-site-packages "${final_path}/venv"
 	set -o nounset
 
 	pip install --upgrade pip
-	pip install weboob html2text simplejson BeautifulSoup4 PyExecJS pdfminer.six
+	pip install weboob html2text simplejson BeautifulSoup4 PyExecJS pdfminer.six --ignore-installed
 )
 
 #=================================================