diff --git a/tool/build-html b/tool/build-html
index 75b38a3..825e9dc 100755
--- a/tool/build-html
+++ b/tool/build-html
@@ -1,3 +1,6 @@
 #!/bin/bash
 
+set -e
+set -o pipefail
+
 ls src/0*/*.{go,sh} | xargs tool/build-html-inner > build/go-by-example.html