diff --git a/Kernel/makeall.sh b/Kernel/makeall.sh
index c24b587a57..6d6321a979 100755
--- a/Kernel/makeall.sh
+++ b/Kernel/makeall.sh
@@ -1,4 +1,9 @@
 #!/bin/sh
+if [ -z "$SERENITY_ROOT" ]; then
+    echo "You must source Toolchain/UseIt.sh to build Serenity."
+    exit 1
+fi
+
 set -e
 
 # Get user and group details for setting qemu disk image ownership