diff --git a/Mk/bsd.port.mk b/Mk/bsd.port.mk
--- a/Mk/bsd.port.mk
+++ b/Mk/bsd.port.mk
@@ -1329,11 +1329,25 @@
 TMPDIR?=	/tmp
 .    endif # defined(PACKAGE_BUILDING)
 
-.    if defined(WITH_DEBUG_PORTS)
-.      if ${WITH_DEBUG_PORTS:M${PKGORIGIN}}
-WITH_DEBUG=	yes
+.    for feature in ${_LIST_OF_WITH_FEATURES}
+.      if defined(WITH_${feature:tu}_PORTS) && defined(WITHOUT_${feature:tu}_PORTS) \
+		&& "${WITH_${feature:tu}_PORTS:M${PKGORIGIN}}" == "${WITHOUT_${feature:tu}_PORTS:M${PKGORIGIN}}" \
+		&& !empty(WITH_${feature:tu}_PORTS:M${PKGORIGIN})
+.        error "Both WITH_${feature:tu}_PORTS and WITHOUT_${feature:tu}_PORTS contain the same origin ${PKGORIGIN}"
 .      endif
-.    endif
+
+.      if ${_DEFAULT_WITH_FEATURES:M${feature}}
+_WITH_OR_WITHOUT=	WITHOUT
+.      else
+_WITH_OR_WITHOUT=	WITH
+.      endif
+
+.      if defined(${_WITH_OR_WITHOUT}_${feature:tu}_PORTS)
+.        if ${${_WITH_OR_WITHOUT}_${feature:tu}_PORTS:M${PKGORIGIN}}
+${_WITH_OR_WITHOUT}_${feature:tu}=	yes
+.        endif
+.      endif
+.    endfor
 
 .    if defined(USE_LTO)
 WITH_LTO=	${USE_LTO}