diff --git a/build.sh b/build.sh
index 146ac4b..d8c6d9c 100755
--- a/build.sh
+++ b/build.sh
@@ -7,7 +7,7 @@ buildp_dispatch() {
 		_build_tgt_meta="" _build_tgt_lc="" _build_tgts_lc=""_pkg_restart="" _pkgs_found="";
 	case "${_msg}" in
 	# Top-level
-	start_build)	shift; build_args "${@}"; build_init; build_checks;
+	start_build)	shift; build_args "${@}"; build_init;
 			ex_rtl_log_set_vnfo_lvl "${ARG_VERBOSE:-0}";
 			ex_rtl_log_msg info "Build started by ${BUILD_USER:=${USER}}@${BUILD_HNAME:=$(hostname)} at ${BUILD_DATE_START}.";
 			ex_rtl_log_env_vars "build (global)" ${DEFAULT_LOG_ENV_VARS};
diff --git a/etc/build.usage b/etc/build.usage
index b065e18..4f2c02f 100644
--- a/etc/build.usage
+++ b/etc/build.usage
@@ -35,11 +35,10 @@ usage: ./build.sh [-a nt32|nt64] [-b debug|release] [-C dir[,..]] [-D kind[,..]]
         -v[v[v[v]]]       Be verbose; -vv: always print package logs; -vvv: set xtrace during package builds; -vvvv: logs fileops.
         --as-needed       Don't build unless the midipix_build repository has received new commits.
         --debug-minipix   Don't strip(1) minipix binaries to facilitate debugging minipix.
-        <target>[ ..]     One of:
-                          host or host_tools, host_tools_deps, host_tools_rpm, host_toolchain_deps, host_toolchain, host_toolchain_mingw32,
-                          native or native_tools, native_toolchain_deps, native_toolchain, native_toolchain_mingw32, native_runtime,
-                          packages_deps or host_packages_deps, native_packages_deps, native_packages_deps_x11,
-                          packages or native_packages.
+        <target>[ ..]     One of: host_packages_deps, host_toolchain, host_toolchain_deps, host_toolchain_mingw32,
+                          host_tools, host_tools_deps, host_tools_rpm, minipix, native_packages, native_packages_deps,
+                          native_packages_deps_x11, native_runtime, native_toolchain, native_toolchain_deps,
+                          native_toolchain_mingw32, and/or native_tools.
 
         ${HOME}/midipix_build.vars, ${HOME}/.midipix_build.vars, and/or ../midipix_build.vars will be sourced if present.
 
diff --git a/subr/build_checks.subr b/subr/build_checks.subr
deleted file mode 100644
index 1955d58..0000000
--- a/subr/build_checks.subr
+++ /dev/null
@@ -1,44 +0,0 @@
-#
-# set -o noglob is assumed.
-#
-
-build_checks() {
-	local __="" _exit="" _pname="";
-	for __ in ${DEFAULT_CHECK_PATH_VARS}; do
-		if [ -z "${___:=$(ex_rtl_get_var_unsafe "${__}")}" ]; then
-			ex_rtl_log_msg failexit "Error: variable \`${__}' is empty or unset.";
-		elif [ "${___#* *}" != "${___}" ]; then
-			ex_rtl_log_msg failexit "Error: variable \`${__}' contains one or more whitespace characters.";
-		fi;
-	done;
-	for __ in ${DEFAULT_CHECK_PREREQ_CMDS} $(eval echo ${DEFAULT_CHECK_PREREQ_FILES_DYNAMIC}) ${DEFAULT_CHECK_PREREQ_FILES}; do
-		if [ "${__#/}" != "${__}" ]; then
-			if [ ! -e "${__}" ]; then
-				ex_rtl_log_msg fail "Error: missing prerequisite file \`${__}'.";
-				_exit=1;
-			fi;
-		else
-			if ! ex_rtl_test_cmd "${__}"; then
-				ex_rtl_log_msg fail "Error: missing prerequisite command \`${__}'.";
-				_exit=1;
-			fi;
-		fi;
-	done;
-	for __ in ${DEFAULT_CHECK_PREREQ_PERL_MODULES}; do
-		if ! perl -M"${__}" -e "" 2>/dev/null; then
-			ex_rtl_log_msg fail "Error: missing prerequisite Perl module \`${__}'.";
-			_exit=1;
-		fi;
-	done;
-	if [ ${_exit:-0} = 1 ]; then
-		exit 1;
-	fi;
-	if ex_rtl_lmatch "${ARG_CLEAN_BUILDS}" , prefix; then
-		ex_rtl_log_msg info "-C prefix specified, cleaning prefix...";
-		for _pname in ${DEFAULT_CLEAR_PREFIX_PATHS}; do
-			ex_rtl_fileop rm ${PREFIX}/${_pname};
-		done;
-	fi;
-};
-
-# vim:filetype=sh
diff --git a/subr/build_init.subr b/subr/build_init.subr
index c7ec7d4..3bd6af1 100644
--- a/subr/build_init.subr
+++ b/subr/build_init.subr
@@ -9,7 +9,7 @@ build_fini() {
 };
 
 build_init() {
-	local __="" _env_vars="" _env_vars_except="" _env_var="" _log_last_fname="" _log_last_ts="";
+	local __="" _env_vars="" _env_vars_except="" _env_var="" _log_last_fname="" _log_last_ts="" _vname="" _vname_val="";
 	set -o noglob; umask 022;
 	if [ -z "${DEFAULT_BUILD_CPUS}" ]\
 	&& [ -e /proc/cpuinfo ]; then
@@ -84,6 +84,20 @@ build_init() {
 		HUP INT TERM USR1 USR2;
 	trap "rm -f "${DEFAULT_BUILD_STATUS_IN_PROGRESS_FNAME}";"	\
 		EXIT;
+	for _vname in ${DEFAULT_CHECK_PATH_VARS}; do
+		_vname_val="$(ex_rtl_get_var_unsafe "${_vname}")";
+		if [ -z "${_vname_val}" ]; then
+			ex_rtl_log_msg failexit "Error: variable \`${_vname}' is empty or unset.";
+		elif [ "${_vname_val#* *}" != "${_vname_val}" ]; then
+			ex_rtl_log_msg failexit "Error: variable \`${_vname}' contains one or more whitespace characters.";
+		fi;
+	done;
+	if ex_rtl_lmatch "${ARG_CLEAN_BUILDS}" , prefix; then
+		ex_rtl_log_msg info "-C prefix specified, cleaning prefix...";
+		for _pname in ${DEFAULT_CLEAR_PREFIX_PATHS}; do
+			ex_rtl_fileop rm "${PREFIX}/${_pname}";
+		done;
+	fi;
 };
 
 # vim:filetype=sh
diff --git a/vars/midipix.vars b/vars/midipix.vars
index f7cbcd6..7a779d5 100644
--- a/vars/midipix.vars
+++ b/vars/midipix.vars
@@ -18,10 +18,14 @@
 : ${PREFIX_RPM:=${PREFIX}/rpm};
 : ${BUILD_DLCACHEDIR:=${PREFIX_ROOT}/dlcache};
 : ${BUILD_WORKDIR:=${PREFIX}/tmp};
-: ${DEFAULT_LOG_ENV_VARS:="
-	ARCH BUILD BUILD_DLCACHEDIR BUILD_WORKDIR DEFAULT_GITROOT
-	HOME PATH PREFIX PREFIX_CROSS PREFIX_MINGW32 PREFIX_MINIPIX
-	PREFIX_NATIVE USER"};
+: ${DEFAULT_CHECK_PATH_VARS:="
+	PREFIX PREFIX_NATIVE PREFIX_CROSS BUILD_DLCACHEDIR BUILD_WORKDIR"};
+: ${DEFAULT_CLEAR_ENV_VARS_EXCEPT:="
+	HOME PATH TERM DEFAULT_TARBALL_SIGN_GPG_KEY USER"};
+: ${DEFAULT_CLEAR_PREFIX_PATHS:="
+	bin i686-nt32-midipix doc include info lib lib64 libexec man minipix minipix_dist native
+	rpm sbin share tmp usr x86_64-nt64-midipix x86_64-w64-mingw32 pkglist.cross pkglist.host
+	pkglist.native SHA256SUMS SHA256SUMS.last"};
 : ${DEFAULT_INSTALL_FILES_DESTDIR:="
 	/=bin /=include /=lib /=lib/pkgconfig /=sbin
 	/=share /=share/doc /=share/info /=share/man
@@ -33,6 +37,10 @@
 	@share/man=man
 	@../lib/pkgconfig=share/pkgconfig
 	@.=usr"};
+: ${DEFAULT_LOG_ENV_VARS:="
+	ARCH BUILD BUILD_DLCACHEDIR BUILD_WORKDIR DEFAULT_GITROOT
+	HOME PATH PREFIX PREFIX_CROSS PREFIX_MINGW32 PREFIX_MINIPIX
+	PREFIX_NATIVE USER"};
 
 # Default flags & variables
 : ${DEFAULT_BUILD_CPUS:=};
@@ -88,24 +96,4 @@
 : ${DEFAULT_TARBALL_MINIPIX_FNAME_PREFIX:=minipix-${ARCH}-${BUILD}.};
 : ${DEFAULT_ZIPDIST_FNAME_PREFIX:=midipix-${ARCH}-${BUILD}.};
 
-# Check & clear predicates
-: ${DEFAULT_CHECK_PATH_VARS:="
-	PREFIX PREFIX_NATIVE PREFIX_CROSS DLCACHEDIR WORKDIR"};
-: ${DEFAULT_CHECK_PREREQ_CMDS:="
-	aclocal autoconf autopoint awk basename bunzip2 find flex gcc git groff gunzip install
-	ld libtool lzma make makeinfo msgfmt nl nroff openssl paste patch python sed sha256sum
-	sort tar tee tic tr uname wget xz"};
-: ${DEFAULT_CHECK_PREREQ_FILES_DYNAMIC:='
-	/usr/share/groff/$(groff -v 2>/dev/null | awk '\''/^GNU groff version /{print $NF}'\'')/tmac/e.tmac'};
-: ${DEFAULT_CHECK_PREREQ_FILES:="
-	/usr/include/gmpxx.h /usr/include/mpc.h /usr/include/mpfr.h"};
-: ${DEFAULT_CHECK_PREREQ_PERL_MODULES:="
-	autodie ExtUtils::MakeMaker"};
-: ${DEFAULT_CLEAR_ENV_VARS_EXCEPT:="
-	HOME PATH TERM DEFAULT_TARBALL_SIGN_GPG_KEY USER"};
-: ${DEFAULT_CLEAR_PREFIX_PATHS:="
-	bin i686-nt32-midipix doc include info lib lib64 libexec man minipix minipix_dist native
-	rpm sbin share tmp usr x86_64-nt64-midipix x86_64-w64-mingw32 pkglist.cross pkglist.host
-	pkglist.native SHA256SUMS SHA256SUMS.last"};
-
 # vim:filetype=sh textwidth=0