diff --git a/stand/i386/pxeldr/Makefile b/stand/i386/pxeldr/Makefile
--- a/stand/i386/pxeldr/Makefile
+++ b/stand/i386/pxeldr/Makefile
@@ -28,6 +28,12 @@
 L=${LOADER_DEFAULT_INTERP}
 .endif
 LOADERBIN= ${BOOTOBJ}/i386/loader_${L}/loader_${L}.bin
+# pxeldr runs in an environment where there's 500k or less of space available
+# due to space for packet buffers, network drivers, etc. While some environments
+# may have a bit more, the limit of 500,000 (488k) provides enough margin to
+# work in a huge array of environments. Larger values may work for specific
+# environments.
+PXELDRSIZE?=500000
 
 CLEANFILES+= ${BOOT}.tmp
 
@@ -43,6 +49,8 @@
 # Note: pxeldr.S assumes a.out and will require changes for ELF if the output
 # format is changed to ELF.
 ${LOADER}: ${LOADERBIN} ${BTXLDR} ${BTXKERN}
+	@set -- `ls -l ${LOADERBIN}` ; x=$$((${PXELDRSIZE}-$$5)); \
+	    echo "$$x bytes available"; test $$x -ge 0
 	btxld -v -f aout -e ${LOADER_ADDRESS} -o ${.TARGET} -l ${BTXLDR} \
 	    -b ${BTXKERN} ${LOADERBIN}