diff --git a/doc/Makefile b/doc/Makefile
index 0a390147..c1bfd499 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -25,7 +25,7 @@ endif
 # //
 # ************************************************************************/
 
-top_srcdir = ..
+top_srcdir ?= ..
 
 PACKAGE       = upx
 VERSION_DATE := $(shell sed -n 's/^.*UPX_VERSION_DATE_ISO .*"\(.*\)".*/\1/p' $(top_srcdir)/src/version.h)
@@ -81,4 +81,5 @@ mostlyclean clean distclean maintainer-clean:
 ###
 
 $(BUILT_SOURCES): $(top_srcdir)/src/version.h $(MAKEFILE_LIST)
+.DELETE_ON_ERROR: $(BUILT_SOURCES)
 
diff --git a/src/stub/Makefile b/src/stub/Makefile
index 2a223525..818275f9 100644
--- a/src/stub/Makefile
+++ b/src/stub/Makefile
@@ -125,9 +125,11 @@ maintainer-clean:
 override T = $(basename $(notdir $@))
 
 # trim (strip) trailing whitespace
-RTRIM := sed -e 's/[ $(tab)]*$$//'
-# squeeze duplicate blank lines, remove empty first & last line
-SQUEEZE := cat --squeeze-blank | sed -e '1{/^$$/d}' -e '$${/^$$/d}'
+RTRIM     := sed -e 's/[ $(tab)]*$$//'
+# squeeze duplicate blank lines, delete empty first & last line
+BLSQUEEZE := $(RTRIM) | cat --squeeze-blank | sed -e '1{/^$$/d}' -e '$${/^$$/d}'
+# delete blank lines
+BLDEL     := $(RTRIM) | sed -e '/^$$/d'
 
 # clear some vars, just in case
 LABEL_PREFIX =
@@ -184,7 +186,7 @@ define tc.default.f-embed_objinfo
 	$(call tc,objcopy) -R .text -R .data -R .bss $1
 	$(call tc,objcopy) -R .comment -R .note -R .note.GNU-stack -R .reginfo $1
 	$(call tc,objdump) -Dr $(tc_objdump_disasm_options) $1 | $(RTRIM) > $1.disasm
-	$(call tc,objdump) -htr -w $1 | $(RTRIM) | $(SQUEEZE) > $1.dump
+	$(call tc,objdump) -htr -w $1 | $(BLSQUEEZE) > $1.dump
 	cat $1.dump >> $1
 endef
 define tc.default.f-objstrip
@@ -714,6 +716,7 @@ $(STUBS): tmp/.tmp-stamp $(MAKEFILE_LIST)
 endif
 -include tmp/*.d
 
+.DELETE_ON_ERROR: %.h %.o
 ifneq ($(strip $(STUBS)),)
 .DELETE_ON_ERROR: $(STUBS)
 endif
diff --git a/src/stub/src/arch/arm/v4a/Makefile.extra b/src/stub/src/arch/arm/v4a/Makefile.extra
index b8636d90..bceab6ff 100644
--- a/src/stub/src/arch/arm/v4a/Makefile.extra
+++ b/src/stub/src/arch/arm/v4a/Makefile.extra
@@ -44,7 +44,8 @@ $c += -I$(top_srcdir)/src
 
 lzma_d_c%.S : lzma_d_c.c
 	$(call tc,gcc) $(PP_FLAGS) -S $< -o tmp/$T.s
-	sed -e '1,/LzmaDecode:/c.arm' -e '/\.size/d' -e '/\.ident/d' -e 's/\.L/$(LABEL_PREFIX)/g' tmp/$T.s | $(RTRIM) > $@
+	cat tmp/$T.s | $(BLDEL) | sed -e '1,/LzmaDecode:/c.arm' -e '/\.size/d' -e '/\.ident/d' -e 's/\.L/$(LABEL_PREFIX)/g' | $(BLDEL) > $@
+	# the following stuff is for debugging only
 	$(call tc,gcc) -c -MF /dev/null $@ -o tmp/$T.o
 	$(call tc,f-objstrip,tmp/$T.o)
 	$(call tc,objcopy) -O binary tmp/$T.o tmp/$T.bin
diff --git a/src/stub/src/arch/arm/v4t/Makefile.extra b/src/stub/src/arch/arm/v4t/Makefile.extra
index 1ac036b7..9c09dbaa 100644
--- a/src/stub/src/arch/arm/v4t/Makefile.extra
+++ b/src/stub/src/arch/arm/v4t/Makefile.extra
@@ -42,7 +42,8 @@ $c += -I$(top_srcdir)/src
 
 lzma_d_c%.S : lzma_d_c.c
 	$(call tc,gcc) $(PP_FLAGS) -S $< -o tmp/$T.s
-	sed -e '1,/LzmaDecode:/c.thumb' -e '/\.size/d' -e '/\.ident/d' -e 's/\.L/$(LABEL_PREFIX)/g' tmp/$T.s | $(RTRIM) > $@
+	cat tmp/$T.s | $(BLDEL) | sed -e '1,/LzmaDecode:/c.thumb' -e '/\.size/d' -e '/\.ident/d' -e 's/\.L/$(LABEL_PREFIX)/g' | $(BLDEL) > $@
+	# the following stuff is for debugging only
 	$(call tc,gcc) -c -MF /dev/null $@ -o tmp/$T.o
 	$(call tc,f-objstrip,tmp/$T.o)
 	$(call tc,objcopy) -O binary tmp/$T.o tmp/$T.bin
diff --git a/src/stub/src/arch/m68k/m68000/Makefile.extra b/src/stub/src/arch/m68k/m68000/Makefile.extra
index f8da7f97..919645d8 100644
--- a/src/stub/src/arch/m68k/m68000/Makefile.extra
+++ b/src/stub/src/arch/m68k/m68000/Makefile.extra
@@ -42,7 +42,7 @@ $c += -I$(top_srcdir)/src
 
 lzma_d_c%.S : lzma_d_c.c
 	$(call tc,gcc) $(PP_FLAGS) -S $< -o tmp/$T.s
-	cat tmp/$T.s | $(RTRIM) | $(SQUEEZE) | sed -e '/^$$/d' -e '1,/LzmaDecode:/d' -e '/\.size/d' -e '/\.ident/d' -e '/\.section/d' -e 's/\.L/$(LABEL_PREFIX)/g' -e '/^[ \t]rts.*/d' -e 's/bsr\.l/bsr.w/' tmp/$T.s | $(RTRIM) > $@
+	cat tmp/$T.s | $(BLDEL) | sed -e '1,/LzmaDecode:/d' -e '/\.size/d' -e '/\.ident/d' -e '/\.section/d' -e 's/\.L/$(LABEL_PREFIX)/g' -e '/^[ $(tab)]rts.*/d' -e 's/bsr\.l/bsr.w/' | $(BLDEL) > $@
 	# the following stuff is for debugging only
 	$(call tc,gcc) -c -MF /dev/null $@ -o tmp/$T.o
 	$(call tc,f-objstrip,tmp/$T.o)