Index: Mk/bsd.default-versions.mk
===================================================================
--- Mk/bsd.default-versions.mk
+++ Mk/bsd.default-versions.mk
@@ -108,11 +108,7 @@
 .      if defined(PKG_BIN)
 # find installed port and use it for dependency
 .        if !defined(OPENSSL_INSTALLED)
-.          if defined(DESTDIR)
-PKGARGS=	-c ${DESTDIR}
-.          else
-PKGARGS=
-.          endif
+PKGARGS=	${DESTDIR:D-c ${DESTDIR}}
 OPENSSL_INSTALLED!=	${PKG_BIN} ${PKGARGS} which -qo ${LOCALBASE}/lib/libcrypto.so || :
 .        endif
 .        if defined(OPENSSL_INSTALLED) && !empty(OPENSSL_INSTALLED)
Index: Mk/bsd.destdir.mk
===================================================================
--- Mk/bsd.destdir.mk
+++ Mk/bsd.destdir.mk
@@ -69,11 +69,7 @@
 
 _DESTDIRMKINCLUDED=	yes
 
-.if defined(WITH_DESTDIR_DEBUG)
-DEBUG_MSG=	${ECHO_MSG} "DEBUG:"
-.else
-DEBUG_MSG=	${TRUE}
-.endif
+DEBUG_MSG=	${WITH_DESTDIR_DEBUG:?${ECHO_MSG} "DEBUG:":${TRUE}}
 
 DESTDIR_ENV_LIST?=
 DESTDIR_ENV=	CHROOTED=yes PATH=${PATH} TERM=${TERM}
Index: Mk/bsd.java.mk
===================================================================
--- Mk/bsd.java.mk
+++ Mk/bsd.java.mk
@@ -268,16 +268,8 @@
 .		else
 _JAVA_VERSION=	${__JAVA_VERSION_LIST}
 .		endif
-.		if defined(JAVA_OS)
-_JAVA_OS=	${JAVA_OS}
-.		else
-_JAVA_OS=	${_JAVA_OS_LIST}
-.		endif
-.		if defined(JAVA_VENDOR)
-_JAVA_VENDOR=	${JAVA_VENDOR}
-.		else
-_JAVA_VENDOR=	${_JAVA_VENDOR_LIST}
-.		endif
+_JAVA_OS=	${JAVA_OS:?${JAVA_OS}:${_JAVA_OS_LIST}}
+_JAVA_VENDOR=	${JAVA_VENDOR:?${JAVA_VENDOR}:${_JAVA_VENDOR_LIST}}
 
 .		for A_JAVA_PORT in ${_JAVA_PORTS_ALL}
 A_JAVA_PORT_INFO:=			${A_JAVA_PORT:S/^/\${_/:S/$/_INFO}/}
Index: Mk/bsd.licenses.mk
===================================================================
--- Mk/bsd.licenses.mk
+++ Mk/bsd.licenses.mk
@@ -169,11 +169,7 @@
 # _LICENSE_COMB		- Copy of LICENSE_COMB (but "single" instead of empty)
 
 _LICENSE?=			${LICENSE}
-.if !defined(LICENSE_COMB)
-_LICENSE_COMB=		single
-.else
-_LICENSE_COMB=		${LICENSE_COMB}
-.endif
+_LICENSE_COMB=		${LICENSE_COMB:?${LICENSE_COMB}:single}
 
 # Check if single or dual/multiple license
 #
Index: Mk/bsd.port.mk
===================================================================
--- Mk/bsd.port.mk
+++ Mk/bsd.port.mk
@@ -1872,13 +1872,8 @@
 MAKE_ARGS+=	${DESTDIRNAME}=${STAGEDIR}
 .endif
 
-.if defined(NO_PREFIX_RMDIR)
-CO_ENV+=	NO_PREFIX_RMDIR=1
-.else
-CO_ENV+=	NO_PREFIX_RMDIR=0
-.endif
+CO_ENV+=	NO_PREFIX_RMDIR=${NO_PREFIX_RMDIR:?1:0}
 
-
 METADIR=		${WRKDIR}/.metadir
 
 PKGPREINSTALL?=		${PKGDIR}/pkg-pre-install
@@ -2167,11 +2162,7 @@
 
 TMPPLIST?=	${WRKDIR}/.PLIST.mktmp
 
-.if defined(PKG_NOCOMPRESS)
-PKG_SUFX?=		.tar
-.else
-PKG_SUFX?=		.txz
-.endif
+PKG_SUFX?=		${PKG_NOCOMPRESS:?.tar:.txz}
 # where pkg(8) stores its data
 PKG_DBDIR?=		/var/db/pkg
 
@@ -3018,11 +3009,7 @@
 			dp_RANDOMIZE_SITES='${_RANDOMIZE_SITES}' \
 			dp_SCRIPTSDIR='${SCRIPTSDIR}' \
 			dp_TARGET='${.TARGET}'
-.if defined(DEVELOPER)
-_DO_FETCH_ENV+= dp_DEVELOPER=yes
-.else
-_DO_FETCH_ENV+= dp_DEVELOPER=
-.endif
+_DO_FETCH_ENV+= dp_DEVELOPER=${DEVELOPER:Dyes}
 
 # Fetch
 
Index: Mk/bsd.port.subdir.mk
===================================================================
--- Mk/bsd.port.subdir.mk
+++ Mk/bsd.port.subdir.mk
@@ -39,11 +39,7 @@
 
 PORTSDIR?=		/usr/ports
 TEMPLATES?=		${PORTSDIR}/Templates
-.if defined(PORTSTOP)
-README=			${TEMPLATES}/README.top
-.else
-README=			${TEMPLATES}/README.category
-.endif
+README=			${TEMPLATES}/README.${PORTSTOP:?top:category}
 MOVEDDIR?=		${PORTSDIR}
 MOVEDFILE?=		MOVED
 
@@ -232,11 +228,7 @@
 IGNOREDIR=	Mk Templates Tools distfiles packages pkg Keywords
 
 .if !target(checksubdirs)
-.if defined(PORTSTOP)
-checksubdirs: checksubdir ${SUBDIR:S/^/_/:S/$/.checksubdirs/}
-.else
-checksubdirs: checksubdir
-.endif
+checksubdirs: checksubdir ${PORTSTOP:D${SUBDIR:S/^/_/:S/$/.checksubdirs/}}
 .endif
 
 .if !target(checksubdir)