Hi. There seems to be an hidden dep here:
cc -W -Wall -Wundef -Wpointer-arith -Wcast-align -Wwrite-strings -Wmissing-declarations -Wuninitialized -Wno-unused-parameter -Wno-unused-but-set-variable -Wimplicit-fallthrough=3 -Wno-redundant-decls -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -I. -Iinclude -Ibuild/OpenBSD-gtk3 -Ifrontends -Icontent/handlers -O2 -DWITH_JPEG -UWITH_PDF_EXPORT -ULIBICONV_PLUG -I/usr/local/include -I/usr/local/include -I/usr/local/include -I/usr/local/include -DWITH_CURL -DWITH_OPENSSL -I/usr/local/include -DUTF8PROC_EXPORTS -DWITH_UTF8PROC -I/usr/local/include -DHWY_SHARED_DEFINE -DWITH_JPEGXL -I/usr/local/include -I/usr/local/include/webp -DWITH_WEBP -I/usr/local/include/libpng16 -DWITH_PNG -I/usr/local/include/ -DWITH_BMP -I/usr/local/include -DWITH_GIF -I/usr/local/include -DWITH_NSPSL -I/usr/local/include -DWITH_NSLOG -DNETSURF_UA_FORMAT_STRING=\""Mozilla/5.0 (%s) NetSurf/%d.%d"\" -DNETSURF_HOMEPAGE=\""about:welcome"\" -DNETSURF_LOG_LEVEL=VERBOSE -DNETSURF_BUILTIN_LOG_FILTER=\""(level:WARNING || cat:jserrors)"\" -DNETSURF_BUILTIN_VERBOSE_FILTER=\""(level:VERBOSE || cat:jserrors)"\" -DSTMTEXPR=1 -I/usr/local/include/librsvg-2.0 -I/usr/local/include/gdk-pixbuf-2.0 -I/usr/local/include -pthread -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -I/usr/local/include/cairo -I/usr/local/include/libpng16 -I/usr/X11R6/include -I/usr/X11R6/include/freetype2 -I/usr/X11R6/include/pixman-1 -DWITH_RSVG -I/usr/local/include/gtk-3.0 -I/usr/local/include/at-spi2-atk/2.0 -I/usr/local/include/at-spi-2.0 -I/usr/X11R6/include -I/usr/local/include/dbus-1.0 -I/usr/local/lib/dbus-1.0/include -I/usr/local/include -I/usr/local/include/gio-unix-2.0 -I/usr/local/include/libepoll-shim -I/usr/X11R6/include/libdrm -I/usr/local/include/pango-1.0 -I/usr/local/include/harfbuzz -I/usr/local/include/fribidi -I/usr/local/include/atk-1.0 -I/usr/local/include/cairo -I/usr/X11R6/include/freetype2 -I/usr/X11R6/include/pixman-1 -I/usr/local/include/gdk-pixbuf-2.0 -I/usr/local/include/libpng16 -pthread -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -I/usr/local/include -pthread -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -I/usr/local/include -pthread -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -std=c99 -Dgtk -Dnsgtk -g -DG_DISABLE_SINGLE_INCLUDES -DG_DISABLE_DEPRECATED -DGTK_DISABLE_SINGLE_INCLUDES -DGTK_MULTIHEAD_SAFE -DPANGO_DISABLE_DEPRECATED -D_BSD_SOURCE -D_DEFAULT_SOURCE -D_XOPEN_SOURCE=700 -D_POSIX_C_SOURCE=200809L -D_NETBSD_SOURCE -DGTK_RESPATH=\"/usr/local/share/netsurf/:./frontends/gtk/res/\" -DWITH_GRESOURCE -DDUK_OPT_HAVE_CUSTOM_H -O2 -pipe -g -MMD -MP -MT 'build/OpenBSD-gtk3/deps/content_handlers_image_jpegxl.d build/OpenBSD-gtk3/content_handlers_image_jpegxl.o' -MF build/OpenBSD-gtk3/deps/content_handlers_image_jpegxl.d -o build/OpenBSD-gtk3/content_handlers_image_jpegxl.o -c content/handlers/image/jpegxl.c warning: unknown warning option '-Wimplicit-fallthrough=3'; did you mean '-Wimplicit-fallthrough'? [-Wunknown-warning-option] content/handlers/image/jpegxl.c:31:10: fatal error: 'jxl/decode.h' file not found #include <jxl/decode.h> ^~~~~~~~~~~~~~ 1 warning and 1 error generated -- Antoine