diff --git a/pester.sh b/pester.sh
index fb7d62fb75..a18c60497f 100755
--- a/pester.sh
+++ b/pester.sh
@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+test -x bin/powershell || { echo >&2 "No bin/powershell, please run './build.sh'"; exit 1; }
+
 ./bin/powershell --noprofile -c "Invoke-Pester test/powershell/$1 -OutputFile pester-tests.xml -OutputFormat NUnitXml -EnableExit"
 failed_tests=$?