diff --git a/ci/spellcheck.sh b/ci/spellcheck.sh
index f1c84a5f..3d61e76a 100755
--- a/ci/spellcheck.sh
+++ b/ci/spellcheck.sh
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set -eu
+
 aspell --version
 
 # Checks project Markdown files for spelling mistakes.
diff --git a/ci/validate.sh b/ci/validate.sh
old mode 100644
new mode 100755
index 9e2cfdf1..04a3bf48
--- a/ci/validate.sh
+++ b/ci/validate.sh
@@ -1,3 +1,7 @@
+#!/bin/bash
+
+set -eu
+
 for file in src/*.md ; do
     echo Checking references in $file
     cargo run --quiet --bin link2print < $file > /dev/null