Index: kitcreator
==================================================================
--- kitcreator
+++ kitcreator
@@ -159,10 +159,37 @@
 
 		break
 	fi
 done
 export TCLSH_NATIVE
+
+# Verify that each component is happy with the environment
+validatefailed="0"
+for pkg in tcl tclvfs zlib ${KITCREATOR_PKGS} kitsh; do
+	failed='0'
+	if [ -f "${pkg}/.success" ]; then
+		continue
+	fi
+
+	if [ -x "${pkg}/validate.sh" ]; then
+		(
+			cd "${pkg}" >/dev/null 2>/dev/null || exit 1
+
+			./validate.sh 3>&1 4>&2 > build.log 2>&1 || exit 1
+		) || failed="1"
+
+		if [ "${failed}" = '1' ]; then
+			echo "Failed pre-requisite check for ${pkg}" >&2
+
+			validatefailed='1'
+		fi
+	fi
+done
+
+if [ "${validatefailed}" = '1' ]; then
+	exit 1
+fi
 
 # Do build
 failedpkgs=""
 buildfailed="0"
 for pkg in tcl tclvfs zlib ${KITCREATOR_PKGS} kitsh; do

ADDED   tcl/validate.sh
Index: tcl/validate.sh
==================================================================
--- /dev/null
+++ tcl/validate.sh
@@ -0,0 +1,10 @@
+#! /usr/bin/env bash
+
+if [ ! -x "$(which patch 2>/dev/null)" ]; then
+	echo "No \"patch\" command."
+	echo "No \"patch\" command." >&4
+
+	exit 1
+fi
+
+exit 0