diff --git a/misc/flag-icons/Makefile b/misc/flag-icons/Makefile
index 21cf09b196fc..7a123012a67d 100644
--- a/misc/flag-icons/Makefile
+++ b/misc/flag-icons/Makefile
@@ -1,37 +1,41 @@
 PORTNAME=	flag-icons
 PORTVERSION=	7.3.2
 DISTVERSIONPREFIX=	v
 CATEGORIES=	misc
 
 MAINTAINER=	danfe@FreeBSD.org
 COMMENT=	Curated collection of all country flags rendered in PNG
 WWW=		https://flagicons.lipis.dev/
 
 LICENSE=	MIT
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
 BUILD_DEPENDS=	convert:graphics/ImageMagick6 # ${IMAGEMAGICK_DEFAULT}
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	lipis
 
 NO_ARCH=	yes
 NO_INSTALL=	yes
 
 FLAGS_TOPDIR=	${PREFIX}/share/icons/${PORTNAME}
 FLAG_SIZES=	16 24 32 48 64 96 128 192 256 # 512 adds 25+ MB for .tbz package
 
 FLAVORS=	plain bordered rounded
 
 .if ${FLAVOR:U:Nplain}
 PKGNAMESUFFIX=	-${FLAVOR}
 .endif
 
+post-extract:
+	cd ${WRKSRC}/flags && ${SH} ${FILESDIR}/makeflags.sh add-missing-flags
+
 do-build:
-	cd ${BUILD_WRKSRC}/flags && ${SH} ${FILESDIR}/makeflags.sh \
-	${FLAVOR} ${STAGEDIR}${FLAGS_TOPDIR}/${FLAVOR} ${FLAG_SIZES}
+	cd ${BUILD_WRKSRC}/flags && JOBS=${MAKE_JOBS_NUMBER} ${SH} \
+		${FILESDIR}/makeflags.sh ${FLAVOR} \
+		${STAGEDIR}${FLAGS_TOPDIR}/${FLAVOR} ${FLAG_SIZES}
 
 post-stage:
 	cd ${STAGEDIR}${PREFIX} && ${FIND} share -type f >> ${TMPPLIST}
 
 .include <bsd.port.mk>
diff --git a/misc/flag-icons/files/makeflags.sh b/misc/flag-icons/files/makeflags.sh
index 160212b7c673..b98888fa1546 100644
--- a/misc/flag-icons/files/makeflags.sh
+++ b/misc/flag-icons/files/makeflags.sh
@@ -1,67 +1,91 @@
+# https://commons.wikimedia.org/wiki/File:Flag_of_Esperanto.svg
+add-esperanto-flag()
+{
+	cat > "$1/epo.svg" << EOD
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" width="$2" height="400">
+<path fill="#FFF" d="m0,0h202v202H0"/>
+<path fill="#090" d="m0,200H200V0H$2V400H0m58-243 41-126 41,126-107-78h133"/>
+</svg>
+EOD
+}
+
+add-missing-flags()
+{
+	add-esperanto-flag 1x1 400
+	add-esperanto-flag 4x3 533
+}
+
+async() { "$@" & }
+
 simple()
 {
-	local comment convert_extra_args destdir height ratio subdir t0 width
+	local comment convert_extra_args destdir flag height i=0 ratio subdir t0 width
 
 	comment=$1; convert_extra_args=$2; destdir=$3; shift 3
 
 	for subdir in ?x?; do
 		ratio=${subdir%x*}/${subdir#*x}
 		for height; do
 			width=$((height * $ratio))
 			mkdir -p "$destdir/${width}x${height}"
 			echo -n "Generating $comment flags ${width}x${height}... "
 			t0=$(date +%s)
 			for flag in $subdir/*.svg; do
-				convert -resize ${width}x${height} $convert_extra_args \
+				i=$((i % ${JOBS:-1}))
+				test $((i+=1)) -eq 1 && wait
+				async convert -resize ${width}x${height} $convert_extra_args \
 				"$flag" "$destdir/${width}x${height}/$(basename "$flag" svg)png"
-			done
+			done; wait
 			echo "finished in $(date -ur $((`date +%s`-t0)) +%M:%S)"
 		done
 	done
 }
 
 plain()
 {
 	simple undecorated -strip "$@"
 }
 
 bordered()
 {
 	simple black-bordered '-shave 1x1 -bordercolor black -border 1 -strip' "$@"
 }
 
 # https://joeldare.com/rounding-image-corners-with-imagemagick
 rounded()
 {
-	local destdir height mask radius ratio subdir t0 width
+	local destdir flag height i=0 mask radius ratio subdir t0 width
 
 	destdir=$1; shift
 	mask=$(mktemp)
 
 	for subdir in ?x?; do
 		ratio=${subdir%x*}/${subdir#*x}
 		for height; do
 			width=$((height * $ratio))
 			radius=$((height / 10))
 
 			convert -size ${width}x${height} xc:none -draw \
 			"roundRectangle 0,0,$((width-1)),$((height-1)),$radius,$radius" \
 			-strip "png:$mask"
 
 			mkdir -p "$destdir/${width}x${height}"
 
 			echo -n "Generating rounded corner flags ${width}x${height}... "
 			t0=$(date +%s)
 			for flag in $subdir/*.svg; do
-				convert -resize ${width}x${height} \
+				i=$((i % ${JOBS:-1}))
+				test $((i+=1)) -eq 1 && wait
+				async convert -resize ${width}x${height} \
 				"$flag" -matte "$mask" \
 				-compose DstIn -composite -strip \
 				"$destdir/${width}x${height}/$(basename "$flag" svg)png"
-			done
+			done; wait
 			echo "finished in $(date -ur $((`date +%s`-t0)) +%M:%S)"
 		done
 	done
 	rm "$mask"
 }
 
 "$@"