--- a/build/check-sync-exceptions
+++ b/build/check-sync-exceptions
@@ -1,12 +1,11 @@
 mach_bootstrap.py
 merge-installrdf.py
 pymake
-png2ico.py
 client.py-args
 client.py-l10n-args
 
 # Ignore detritus left lying around by editing tools.
 *~
 .#*
 #*#
 *.orig

--- a/config/config.mk
+++ b/config/config.mk
@@ -695,21 +695,16 @@ install_cmd ?= $(INSTALL) $(1)
 SYSINSTALL  = $(NSINSTALL) -t
 # This isn't necessarily true, just here
 sysinstall_cmd = install_cmd
 
 # Directory nsinstall.
 DIR_INSTALL = $(INSTALL)
 dir_install_cmd = install_cmd
 
-# png to ico converter. The function takes 5 arguments, in order: source png
-# file, left, top, size, output ico file.
-png2ico = $(PYTHON) $(MOZILLA_DIR)/config/pythonpath.py \
-  -I$(topsrcdir)/build/pypng $(topsrcdir)/build/png2ico.py $(1) $(2) $(3) $(4) $(5)
-
 #
 # Localization build automation
 #
 
 # Because you might wish to "make locales AB_CD=ab-CD", we don't hardcode
 # MOZ_UI_LOCALE directly, but use an intermediate variable that can be
 # overridden by the command line. (Besides, AB_CD is prettier).
 AB_CD = $(MOZ_UI_LOCALE)

--- a/mail/app/Makefile.in
+++ b/mail/app/Makefile.in
@@ -83,22 +83,30 @@ ifdef _MSC_VER
 # Always enter a Windows program through wmain, whether or not we're
 # a console application.
 WIN32_EXE_LDFLAGS += -ENTRY:wmainCRTStartup
 endif
 
 ifeq ($(OS_ARCH),WINNT)
 # Extract the icons we care about embedding into the EXE
 mailtoolbar = $(topsrcdir)/mail/themes/windows/mail/icons/mail-toolbar-aero.png
+
+# png to ico converter. The function takes 5 arguments, in order: source png
+# file, left, top, size, output ico file.
+png2ico = $(PYTHON) $(srcdir)/png2ico.py $(1) $(2) $(3) $(4) $(5)
+
 # Each icon is 18x18 in the toolbar, and we want a 16x16 icon here, so we cut
 # off a pixel at each end.
-embedded-icons::
+write-message.ico: $(mailtoolbar) $(srcdir)/png2ico.py
 	$(call png2ico,$(mailtoolbar),19,1,16,write-message.ico)
+
+address-book.ico: $(mailtoolbar) $(srcdir)/png2ico.py
 	$(call png2ico,$(mailtoolbar),37,1,16,address-book.ico)
 
+embedded-icons:: write-message.ico address-book.ico
 GARBAGE += write-message.ico address-book.ico
 
 RCINCLUDE = splash.rc
 # Rebuild thunderbird.exe if the manifest changes - it's included by splash.rc.
 # (this dependency should really be just for thunderbird.exe, not other targets)
 EXTRA_DEPS += $(PROGRAM).manifest
 ifndef GNU_CC
 RCFLAGS += -DMOZ_THUNDERBIRD -I$(srcdir)

rename from build/pypng/png.py
rename to mail/app/png.py

rename from build/png2ico.py
rename to mail/app/png2ico.py