diff --git a/src/Makefile b/src/Makefile
index 8adb4aa9..2f094995 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -72,6 +72,7 @@ ifeq ($(findstring clang,$(CXX)),)
 CXXFLAGS += -fno-delete-null-pointer-checks
 endif
 CXXFLAGS += -fno-strict-aliasing -fwrapv
+CXXFLAGS += -funsigned-char
 CXXFLAGS += -Wall -W -Wcast-align -Wcast-qual -Wmissing-declarations -Wpointer-arith -Wshadow -Wwrite-strings
 CXXFLAGS_WERROR ?= -Werror
 CXXFLAGS += $(CXXFLAGS_WERROR)
@@ -85,16 +86,19 @@ compress_lzma$(objext) filteri$(objext) : CXXFLAGS := $(filter-out $(CXXFLAGS_SA
 endif
 
 
-all: check-whitespace upx$(exeext) | ./.depend
+all: upx$(exeext) | ./.depend
 .DELETE_ON_ERROR: upx$(exeext) $(upx_OBJECTS) ./.depend
 
 upx$(exeext): $(upx_OBJECTS) $(upx_DEPENDENCIES)
 	$($(notdir $@).PRE_LINK_STEP)
 	$(strip $(CXXLD) $(call e,CPPFLAGS) $(call e,CXXFLAGS) $(call e,LDFLAGS) -o $@ $(upx_OBJECTS) $(call e,LDADD) $(call e,LIBS))
 	$($(notdir $@).POST_LINK_STEP)
+	$(CHECK_WHITESPACE)
 
 %.o : %.cpp | ./.depend
 	$(strip $(CXX) $(call e,CPPFLAGS) $(call e,CXXFLAGS) -o $@ -c $<)
+%.cpp.ii : %.cpp | ./.depend
+	$(strip $(CXX) $(call e,CPPFLAGS) $(call e,CXXFLAGS) -o $@ -E $<)
 
 ifeq ($(BUILD_USE_DEPEND),1)
 ./.depend: $(sort $(wildcard $(srcdir)/*.cpp $(srcdir)/*.h)) $(MAKEFILE_LIST)
@@ -106,8 +110,13 @@ else
 .PHONY: ./.depend
 endif
 
+CHECK_WHITESPACE =
 ifeq ($(shell uname),Linux)
-check-whitespace : ; bash $(top_srcdir)/src/stub/scripts/check_whitespace.sh $(top_srcdir)
+CHECK_WHITESPACE = $(top_srcdir)/src/stub/scripts/check_whitespace.sh $(top_srcdir)
+ifneq ($(wildcard $(top_srcdir)/.git/.),)
+CHECK_WHITESPACE = $(top_srcdir)/src/stub/scripts/check_whitespace_git.sh $(top_srcdir)
+endif
+check-whitespace : ; $(CHECK_WHITESPACE)
 endif
 .PHONY: check-whitespace
 
diff --git a/src/p_djgpp2.cpp b/src/p_djgpp2.cpp
index 472fa8f5..0b50edb9 100644
--- a/src/p_djgpp2.cpp
+++ b/src/p_djgpp2.cpp
@@ -344,7 +344,7 @@ void PackDjgpp2::pack(OutputFile *fo)
 
     // because of a feature (bug?) in stub.asm we need some padding
     memcpy(obuf+data->size, "UPX", 3);
-    data->size = ALIGN_UP(data->size, 4);
+    data->size = ALIGN_UP(data->size, 4u);
 
     linker->defineSymbol("DJ2MAIN1", coff_hdr.a_entry);
     relocateLoader();
diff --git a/src/p_ps1.cpp b/src/p_ps1.cpp
index aa7a148e..6d792669 100644
--- a/src/p_ps1.cpp
+++ b/src/p_ps1.cpp
@@ -547,7 +547,7 @@ void PackPs1::pack(OutputFile *fo)
 
     const int lsize = getLoaderSize();
 
-    unsigned filelen = ALIGN_UP(ih.tx_len, 4);
+    unsigned filelen = ALIGN_UP(ih.tx_len, 4u);
 
     const unsigned decomp_data_start = ih.tx_ptr;
     const unsigned comp_data_start = (decomp_data_start + filelen + overlap) - ph.c_len;
@@ -594,7 +594,7 @@ void PackPs1::pack(OutputFile *fo)
     if (!opt->ps1_exe.no_align || !isCon)
     {
         pad = oh.tx_len;
-        oh.tx_len = ALIGN_UP(oh.tx_len, CD_SEC);
+        oh.tx_len = ALIGN_UP(oh.tx_len, CD_SEC+0u);
         pad = oh.tx_len - pad;
         oh.tx_ptr -= pad;
     }
diff --git a/src/pefile.cpp b/src/pefile.cpp
index f2376d80..7539e163 100644
--- a/src/pefile.cpp
+++ b/src/pefile.cpp
@@ -330,7 +330,7 @@ void PeFile::Reloc::finish(upx_byte *&p,unsigned &siz)
         {
             prev = pos;
             *rel1 = 0;
-            rel->size = ALIGN_UP(ptr_diff(rel1,rel),4);
+            rel->size = ALIGN_UP(ptr_diff(rel1,rel), 4);
             newRelocPos((char *)rel + rel->size);
             rel->pagestart = (pos >> 4) &~ 0xfff;
         }
@@ -1177,7 +1177,7 @@ void PeFile::Export::build(char *newbase, unsigned newoffs)
 
 void PeFile::processExports(Export *xport) // pass1
 {
-    soexport = ALIGN_UP(IDSIZE(PEDIR_EXPORT),4);
+    soexport = ALIGN_UP(IDSIZE(PEDIR_EXPORT),4u);
     if (soexport == 0)
         return;
     if (!isdll && opt->win32_pe.compress_exports)
@@ -1258,7 +1258,7 @@ void PeFile::processTls1(Interval *iv,
     COMPILE_TIME_ASSERT(sizeof(tls) == tls_traits<LEXX>::sotls)
     COMPILE_TIME_ASSERT_ALIGNED1(tls)
 
-    if ((sotls = ALIGN_UP(IDSIZE(PEDIR_TLS),4)) == 0)
+    if ((sotls = ALIGN_UP(IDSIZE(PEDIR_TLS),4u)) == 0)
         return;
 
     const tls * const tlsp = (const tls*) (ibuf + IDADDR(PEDIR_TLS));
@@ -1508,7 +1508,7 @@ const upx_byte *PeFile::Resource::ntype() const
 
 unsigned PeFile::Resource::size() const
 {
-    return ALIGN_UP(current->data.size,4);
+    return ALIGN_UP(current->data.size, 4u);
 }
 
 unsigned PeFile::Resource::offs() const
diff --git a/src/stub/scripts/check_whitespace.sh b/src/stub/scripts/check_whitespace.sh
index bffb987d..051ec689 100755
--- a/src/stub/scripts/check_whitespace.sh
+++ b/src/stub/scripts/check_whitespace.sh
@@ -14,8 +14,10 @@ find . \
     -type f -iname '*.bat' -prune -o \
     -type f -iname '*.exe' -prune -o \
     -type f -iname '*.pdf' -prune -o \
+    -type f -iname '*.swp' -prune -o \
     -type f -print0 | LC_ALL=C sort -z | \
 xargs -0r perl -n -e '
+    #print("$ARGV\n");
     if (m,[\r\x1a],) { print "ERROR: DOS EOL detected $ARGV: $_"; exit(1); }
     if (m,([ \t]+)$,) {
         # allow exactly two trailing spaces for GitHub flavoured Markdown in .md files
diff --git a/src/stub/scripts/check_whitespace_git.sh b/src/stub/scripts/check_whitespace_git.sh
new file mode 100755
index 00000000..c04db8c2
--- /dev/null
+++ b/src/stub/scripts/check_whitespace_git.sh
@@ -0,0 +1,30 @@
+#! /usr/bin/env bash
+## vim:set ts=4 sw=4 et:
+set -e; set -o pipefail
+
+# Copyright (C) Markus Franz Xaver Johannes Oberhumer
+
+[[ -z $1 ]] || cd "$1" || exit 1
+[[ -d .git ]] || exit 1
+
+# info: cannot use "-z" as that needs GNU sed 4.2.2 which is not installed on Ubuntu 12.04
+git ls-files --full-name | sed 's/^/\.\//' |\
+sed -e '/lzma-sdk$/d' -e '/\.exe$/d' |\
+LC_ALL=C sort | \
+xargs -r perl -n -e '
+    #print("$ARGV\n");
+    if (m,[\r\x1a],) { print "ERROR: DOS EOL detected $ARGV: $_"; exit(1); }
+    if (m,([ \t]+)$,) {
+        # allow exactly two trailing spaces for GitHub flavoured Markdown in .md files
+        if ($1 ne "  " || $ARGV !~ m,\.md$,) {
+            print "ERROR: trailing whitespace detected $ARGV: $_"; exit(1);
+        }
+    }
+    if (m,\t,) {
+       if ($ARGV =~ m,(^|/)\.gitmodules$,) { }
+       elsif ($ARGV =~ m,(^|/)(gnu|m)?make(file|vars),i) { }
+       elsif ($ARGV =~ m,/tmp/.*\.(disasm|dump)$,) { }
+       elsif ($ARGV =~ m,/src/stub/src/arch/.*\.S$,) { }
+       else { print "ERROR: hard TAB detected $ARGV: $_"; exit(1); }
+    }
+' || exit 1