diff --git a/Makefile b/Makefile
index 5461ce9..2920007 100644
--- a/Makefile
+++ b/Makefile
@@ -773,7 +773,18 @@ $(BUILD)/cmd/%: cmd/%/main.c $(ULIB)
 	$(LD) $(LDFLAGS) $(LD_LOWBASE) -e _start -Ttext 0x4000 -o $@ $(BUILD)/cmd/$*.o $(ULIB)
 	$(OBJCOPY) -S $@
 
+# rm before cp, and it is not tidiness.
+#
+# toybox installs its 236 applets as hard links to one multicall binary, and
+# some of those names collide with first-party programs here -- /bin/ping is
+# both. `cp` onto an existing hard link writes *through* it, so copying this
+# program over the applet of the same name replaced the contents of the shared
+# inode, and every one of the 236 links became this program. `cat` ran ping.
+#
+# It was invisible until the applets became links: while they were separate
+# copies, overwriting one affected exactly one.
 $(SYSROOT)/bin/%: $(BUILD)/cmd/% | $(SYSROOT)/bin
+	rm -f $@
 	cp $< $@
 	chmod 755 $@
 
@@ -971,12 +982,19 @@ $(BUILD)/sysroot.stamp: sysroot-install
 #   - build/fs.img is no longer built by anything, since SchFS became the root,
 #     so pointing at it meant QEMU refused to start at all;
 #   - at FSSIZE blocks it would now be ~600 MB, because BSIZE went from 1024 to
-#     4096. 16 MB is plenty to read one block from.
+#     4096. The size is load-bearing: tools/windows/bootcheck.ps1 asserts on
+#     READ CAPACITY returning 32768 sectors of 512 bytes, which is this.
+#
+#     --exclude bin, because this image exists to prove the USB driver can read
+#     a block and for no other reason. mkfs writes each hard link as its own
+#     copy, so once toybox's 236 applets became links to one binary the /bin
+#     tree expanded to more than 60 MB on the way in -- 236 copies of something
+#     nothing here will ever execute.
 USBSTICK = $(BUILD)/usbstick.img
 $(USBSTICK): $(MKFS) $(BUILD)/sysroot.stamp
 	@mkdir -p $(BUILD)
 	@rm -f $@
-	$(MKFS) $@ --size 4096 --sysroot $(SYSROOT)
+	$(MKFS) $@ --size 4096 --exclude bin --sysroot $(SYSROOT)
 
 usbstick: $(USBSTICK)
 
diff --git a/ports/toybox/Makefile b/ports/toybox/Makefile
index 3e9ff53..2d7d786 100644
--- a/ports/toybox/Makefile
+++ b/ports/toybox/Makefile
@@ -10,6 +10,18 @@
 
 include ../mk/port.mk
 
+# Applets SchOS provides itself, which toybox must not link over.
+#
+# The two collide by name, and the collision is worse than a duplicate: the
+# applets are hard links to one multicall binary, so whichever install runs
+# second wins *for all 236 of them*. Installing first-party ping over the
+# applet replaced the shared inode and every applet became ping; installing
+# the applet over first-party ping put it back and lost the real one.
+#
+# SchOS's ping talks to its own lwIP stack and knows there is no resolver yet.
+# toybox's would be the wrong answer even if it worked.
+TOYBOX_SKIP = ping
+
 TOYBOX_VERSION := 0.8.12
 TOYBOX_URL     := http://landley.net/toybox/downloads/toybox-$(TOYBOX_VERSION).tar.gz
 TOYBOX_SHA256  := ad88a921133ae2231d9f2df875ec0bd42af4429145caea7d7db9e02208a6fd2e
@@ -67,6 +79,7 @@ $(BUILDDIR)/toybox.installed: $(BUILDDIR)/toybox | $(SYSROOT)/bin
 	cp $< $(SYSROOT)/bin/toybox
 	chmod 755 $(SYSROOT)/bin/toybox
 	@for a in $$($(BUILDDIR)/toybox); do \
+	    case " $(TOYBOX_SKIP) " in *" $$a "*) continue ;; esac; \
 	    rm -f $(SYSROOT)/bin/"$$a"; \
 	    ln $(SYSROOT)/bin/toybox $(SYSROOT)/bin/"$$a" 2>/dev/null \
 	      || cp $< $(SYSROOT)/bin/"$$a"; \