diff --git a/.github/scripts/build.sh b/.github/scripts/build.sh
index 4e9b1556c..64b6cc9fc 100755
--- a/.github/scripts/build.sh
+++ b/.github/scripts/build.sh
@@ -1,6 +1,7 @@
 #!/bin/bash
 
 set -e
+set -u
 set -o pipefail
 
 error() {
@@ -14,4 +15,4 @@ cd cpython/Doc || exit 1
 mkdir -p locales/"$LOCALE"/
 ln -sfn "$(realpath ../../docs)" locales/"$LOCALE"/LC_MESSAGES
 pip3 install -q -r requirements.txt
-sphinx-build -b dummy -d build/doctrees  -j auto -D language=$LOCALE -D gettext_compact=0 -W --keep-going -W . build/html 2> >(error)
\ No newline at end of file
+sphinx-build -b dummy -d build/doctrees  -j auto -D language=$LOCALE -D gettext_compact=0 -W --keep-going -W . build/html 2> >(error)
diff --git a/.github/scripts/update.sh b/.github/scripts/update.sh
index 4a15d3095..0f2231d9f 100755
--- a/.github/scripts/update.sh
+++ b/.github/scripts/update.sh
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set -u
+
 cd cpython || exit 1
 
 # Restore git timestamp for enabling build cache