diff --git a/appveyor.yml b/appveyor.yml
index 95271f3..ebe3d27 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -52,8 +52,7 @@ for:
     - mypy --ignore-missing-imports pyqstrat/
     - flake8 --ignore W291,W293,W503,E402,E701,E275,E741 --max-line-length=160 pyqstrat/
     # run notebooks and exit on first error
-    - find pyqstrat/notebooks -name '*.ipynb' \( -exec sh -c 'trap "exit \$?" EXIT; ipython "$0"' {} \; -o  -quit \)
-
+    - find pyqstrat/notebooks -name '*.ipynb' | xargs -n1 sh -c 'ipython $0 || exit 255'
 
 -
   matrix:
diff --git a/build.sh b/build.sh
index 73b7430..d5046cb 100755
--- a/build.sh
+++ b/build.sh
@@ -9,7 +9,7 @@ mypy --ignore-missing-imports pyqstrat/
 flake8 --ignore W291,W293,W503,E402,E701,E275,E741 --max-line-length=160 --extend-exclude notebooks pyqstrat/
 
 # run notebooks and exit on first error
-find pyqstrat/notebooks -name '*.ipynb' \( -exec sh -c 'trap "exit \$?" EXIT; ipython "$0"' {} \; -o  -quit \)
+find pyqstrat/notebooks -name '*.ipynb' | xargs -n1 sh -c 'ipython $0 || exit 255'
 
 # build docs
 rm -Rf ./docs/*