Check for tabs in the linter
-#!/bin/sh
-luacheck pallene/ spec/ examples/ "$@"
+#!/bin/bash
+
+srcdirs=(pallene/ spec/ examples/)
+
+# Lint our Lua code
+luacheck "${srcdirs[@]}" "$@" || exit 1
+
+# Also check if there is tab-based indentation. Luacheck doesn't do this.
+tab=' '
+if
+ grep --recursive \
+ --include='*.c' \
+ --include='*.lua' \
+ --include='*.pln' \
+ "^$tab" "${srcdirs[@]}"
+then
+ echo "Detected tab-based indentation"
+ exit 1
+fi
