diff --git a/thunderbird-makebug.patch b/thunderbird-makebug.patch
new file mode 100644
index 0000000..9a09e10
--- /dev/null
+++ b/thunderbird-makebug.patch
@@ -0,0 +1,12 @@
+diff -up thunderbird-3.0/mozilla/modules/libpr0n/build/Makefile.in.makebug thunderbird-3.0/mozilla/modules/libpr0n/build/Makefile.in
+--- thunderbird-3.0/mozilla/modules/libpr0n/build/Makefile.in.makebug	2009-07-15 22:37:19.000000000 +0200
++++ thunderbird-3.0/mozilla/modules/libpr0n/build/Makefile.in	2009-07-30 16:10:37.000000000 +0200
+@@ -103,7 +103,7 @@ EXTRA_DSO_LDOPTS = \
+ GARBAGE += _img_list nsImgBuildDefines.h
+ 
+ export::
+-	@{ \
++	@{ set \
+ 	$(foreach d,$(filter-out icon,$(MOZ_IMG_DECODERS)), \
+ 		echo "#define IMG_BUILD_DECODER_${d}";) \
+ 	$(foreach d,$(MOZ_IMG_ENCODERS), \
diff --git a/thunderbird.spec b/thunderbird.spec
index 99a44f2..cf6a818 100644
--- a/thunderbird.spec
+++ b/thunderbird.spec
@@ -37,7 +37,7 @@ Patch1:         mozilla-jemalloc.patch
 Patch2:         thunderbird-shared-error.patch
 Patch3:         xulrunner-elif.patch
 Patch4:         thunderbird-pango.patch
-Patch4:         thunderbird-makebug.patch
+Patch5:         thunderbird-makebug.patch
 
 %if %{official_branding}
 # Required by Mozilla Corporation