diff --git a/.appveyor.yml b/.appveyor.yml
index 441a7238..a698ed2f 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -4,7 +4,7 @@
 os: Visual Studio 2015
 
 environment:
-  global: { TRAVIS_OS_NAME: windows, C: "", B: release, CROSS: "", T: "" }
+  global: { TRAVIS_OS_NAME: windows, CROSS: "", C: "", B: release, T: "" }
   matrix:
     - { C: msvc-10.0-x86, CL_VERSION: 16.00, VS_VERSION: 2010 }
 ### - { C: msvc-10.0-x64, CL_VERSION: 16.00, VS_VERSION: 2010 } # AppVeyor: x64 compiler is not installed
@@ -20,6 +20,8 @@ environment:
 init:
   - git config --global core.autocrlf input
   - where bash & where cat & where curl & where git & where sed & where tar
+# - bash --version & git --version & sed --version & tar --version
+  - git --version & bash --version
 # - dir "c:\Program Files\Git\usr\bin"
 # - dir "c:\cygwin\bin"
 # - dir "c:\mingw\bin"
diff --git a/.circle.yml b/.circle.yml
index f955457d..5c0d0b57 100644
--- a/.circle.yml
+++ b/.circle.yml
@@ -9,9 +9,9 @@ branches:
 machine:
   environment:
     TRAVIS_OS_NAME: linux
+    CROSS:
     C: gcc-4.8-m64
     B: release
-    CROSS:
     T:
 
 checkout:
diff --git a/.github/travis_build.sh b/.github/travis_build.sh
index 0a591284..9ccdc10b 100644
--- a/.github/travis_build.sh
+++ b/.github/travis_build.sh
@@ -24,35 +24,11 @@ echo "$CC --version"; $CC --version
 echo "$CXX --version"; $CXX --version
 echo
 
-# whitespace
+# check whitespace
 if [[ $TRAVIS_OS_NAME == linux ]]; then
 cd / && cd $upx_SRCDIR || exit 1
 echo "Checking source code for whitespace violations..."
-find . \
-    -type d -name '.git' -prune -o \
-    -type d -name '.hg' -prune -o \
-    -type d -name 'build' -prune -o \
-    -type d -name 'tmp' -prune -o \
-    -type f -iname '*.bat' -prune -o \
-    -type f -iname '*.exe' -prune -o \
-    -type f -iname '*.pdf' -prune -o \
-    -type f -print0 | LC_ALL=C sort -z | \
-xargs -0r perl -n -e '
-    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
+bash ./src/stub/scripts/check_whitespace.sh || exit 1
 echo "  Passed."
 fi # linux
 
@@ -64,7 +40,7 @@ set -x
 
 cd / && cd $ucl_BUILDDIR || exit 1
 if [[ -n $BM_CROSS || $TRAVIS_OS_NAME == windows ]]; then
-    # configure is too old
+    # ucl-1.03/configure is too old - build manually
     rm -f ./*.o libucl.a
     $CC -O2 -I$ucl_SRCDIR/include -I$ucl_SRCDIR -c $ucl_SRCDIR/src/*.c
     $AR rcs libucl.a *.o
@@ -81,12 +57,13 @@ fi
 # build zlib
 #
 
-if [[ $BUILD_LOCAL_ZLIB ]]; then
+if [[ $BUILD_LOCAL_ZLIB == 1 ]]; then
     cd / && cd $zlib_BUILDDIR || exit 1
+    # build manually
     rm -f ./*.o libz.a
     $CC -O2 -c $zlib_SRCDIR/*.c
     $AR rcs libz.a *.o
-fi # BUILD_LOCAL_ZLIB
+fi
 
 #
 # build UPX
@@ -97,7 +74,7 @@ cd / && cd $upx_BUILDDIR || exit 1
 make="make -f $upx_SRCDIR/src/Makefile"
 EXTRA_CPPFLAGS="$EXTRA_CPPFLAGS -DUCL_NO_ASM"
 EXTRA_LDFLAGS="$EXTRA_LDFLAGS -L$ucl_BUILDDIR/src/.libs"
-if [[ $BUILD_LOCAL_ZLIB ]]; then
+if [[ $BUILD_LOCAL_ZLIB == 1 ]]; then
     EXTRA_CPPFLAGS="$EXTRA_CPPFLAGS -I$zlib_SRCDIR"
     EXTRA_LDFLAGS="$EXTRA_LDFLAGS -L$zlib_BUILDDIR"
 fi
@@ -124,11 +101,11 @@ if [[ $BM_B =~ (^|\+)ALLOW_FAIL($|\+) ]]; then
 fi
 export EXTRA_CPPFLAGS EXTRA_CXXFLAGS EXTRA_LDFLAGS
 
-$make
+[[ -z $upx_exeext ]] && upx_exeext=.out
+$make exeext=$upx_exeext
 
-[[ -z $exeext ]] && exeext=.out
-ls -l upx${exeext}
-$SIZE upx${exeext} || true
-file upx${exeext}
+ls -l upx${upx_exeext}
+$SIZE upx${upx_exeext} || true
+file upx${upx_exeext}
 
 exit 0
diff --git a/.github/travis_init.sh b/.github/travis_init.sh
index 00bd4d16..19066f41 100644
--- a/.github/travis_init.sh
+++ b/.github/travis_init.sh
@@ -6,12 +6,12 @@
 #set -x # debug
 umask 022
 
-# rename short Build-Matrix variables to more readable names
+# rename short variables to more readable Build-Matrix BM_ names
 #   C is COMPILER
-#   B is BUILD_TYPE
-#   T is TESTSUITE_FLAGS
-BM_C=$C; BM_B=$B; BM_CROSS=$CROSS; BM_T=$T
-unset C B CROSS T
+#   B is BUILD_OPTIONS
+#   T is TESTSUITE_OPTIONS
+BM_CROSS=$CROSS; BM_C=$C; BM_B=$B; BM_T=$T
+unset CROSS C B T
 [[ -z $BM_C ]] && BM_C=gcc
 [[ -z $BM_B ]] && BM_B=release
 
@@ -41,7 +41,7 @@ CC=false CXX=false SCAN_BUILD=false
 AR=ar SIZE=size
 if [[ -n $APPVEYOR_JOB_ID ]]; then
     BUILD_LOCAL_ZLIB=1
-    export exeext=.exe
+    upx_exeext=.exe
     # dir c:\cygwin
     case $BM_C in
         gcc-m32 | gcc-4.9-m32)
@@ -68,7 +68,7 @@ if [[ -n $BM_CROSS ]]; then
     case $BM_CROSS-$BM_C in
         arm-linux-gnueabi-gcc | arm-linux-gnueabi-gcc-4.6)
             export upx_EXTRA_LDFLAGS="-static-libgcc -static-libstdc++"
-            [[ -z $upx_qemu ]] && upx_qemu="qemu-arm-static -L/usr/arm-linux-gnueabi"
+            [[ -z $upx_qemu ]] && upx_qemu="qemu-arm -L/usr/arm-linux-gnueabi"
             x=arm-linux-gnueabi; AR="$x-ar"; CC="$x-gcc"; CXX="$x-g++" ;;
         arm-linux-gnueabihf-gcc | arm-linux-gnueabihf-gcc-4.6)
             export upx_EXTRA_LDFLAGS="-static-libgcc -static-libstdc++"
@@ -142,22 +142,28 @@ done
 [[ -z $lcov_OUTPUTDIR ]] && lcov_OUTPUTDIR=$(readlink -mn -- "$toptop_bdir/.lcov-results")
 unset toptop_builddir toptop_bdir
 
-# ensure absolute dirs
+# ensure absolute directories
+make_absolute() {
+    while [[ $# -gt 0 ]]; do
+        if [[ -n ${!1} ]]; then
+            d=$(readlink -mn -- "${!1}")
+            eval $1="$d"
+        fi
+        shift
+    done
+}
 for var_prefix in ucl upx upx_testsuite zlib; do
-for var_suffix in _BUILDDIR _SRCDIR; do
-    var_name=${var_prefix}${var_suffix}
-    if [[ -n ${!var_name} ]]; then
-        d=$(readlink -mn -- "${!var_name}")
-        eval $var_name="$d"
-    fi
+    for var_suffix in _BUILDDIR _SRCDIR; do
+        make_absolute ${var_prefix}${var_suffix}
+    done
 done
-done
-unset var_name var_prefix var_suffix
+make_absolute lcov_OUTPUTDIR
+unset var_prefix var_suffix
 
 print_settings() {
     local v var_prefix var_suffix
     # Build Matrix
-    for v in TRAVIS_OS_NAME BM_C BM_B BM_CROSS BM_T; do
+    for v in TRAVIS_OS_NAME BM_CROSS BM_C BM_B BM_T; do
         [[ -n ${!v} ]] && echo "${v}='${!v}'"
     done
     # BM_C related
@@ -166,8 +172,8 @@ print_settings() {
         v=EXTRA_${v}
         [[ -n ${!v} ]] && echo "${v}='${!v}'"
     done
-    # dirs and other info
-    for v in TRAVIS_XCODE_SDK UPX_UCLDIR; do
+    # directories and other info
+    for v in TRAVIS_XCODE_SDK UPX_UCLDIR lcov_OUTPUTDIR; do
         [[ -n ${!v} ]] && echo "${v}='${!v}'"
     done
     for var_prefix in ucl upx upx_testsuite zlib; do
@@ -179,5 +185,4 @@ print_settings() {
     ##env | LC_ALL=C sort
 }
 
-
 true
diff --git a/.github/travis_testsuite_1.sh b/.github/travis_testsuite_1.sh
index 3695f8bb..6c43cbc8 100644
--- a/.github/travis_testsuite_1.sh
+++ b/.github/travis_testsuite_1.sh
@@ -16,7 +16,6 @@ argv0="$0"; argv0dir=$(readlink -en -- "$0"); argv0dir=$(dirname "$argv0dir")
 fi
 source "$argv0dir/travis_init.sh" || exit 1
 
-# BM_T is TESTSUITE_FLAGS
 if [[ $BM_T =~ (^|\+)SKIP($|\+) ]]; then
     echo "UPX testsuite SKIPPED."
     exit 0
@@ -58,32 +57,33 @@ testsuite_check_sha() {
         diff -u $1/.sha256sums.expected $1/.sha256sums.current || true
         #exit 1
         exit_code=1
+        let num_errors+=1 || true
     fi
     echo
 }
 
 testsuite_run_compress() {
     testsuite_header $testdir
-    local f ff
-    for f in $upx_testsuite_SRCDIR/files/packed/*/upx-3.91*; do
+    local f
+    for f in t01_decompressed/*/*; do
         testsuite_split_f $f
         [[ -z $fb ]] && continue
         mkdir -p $testdir/$fsubdir
-        ff=t01_decompressed/$fsubdir/$fb
-        $upx_exe --prefer-ucl "$@" $ff -o $testdir/$fsubdir/$fb
+        $upx_run --prefer-ucl "$@" $f -o $testdir/$fsubdir/$fb
     done
     testsuite_check_sha $testdir
-    $upx_exe -l $testdir/*/*
-    $upx_exe --file-info $testdir/*/*
-    $upx_exe -t $testdir/*/*
+    $upx_run -l $testdir/*/*
+    $upx_run --file-info $testdir/*/*
+    $upx_run -t $testdir/*/*
 }
 
 # /***********************************************************************
 # // init
 # ************************************************************************/
 
-#set -x
+#set -x # debug
 exit_code=0
+num_errors=0
 
 if [[ $BM_T =~ (^|\+)ALLOW_FAIL($|\+) ]]; then
     echo "ALLOW_FAIL"
@@ -93,32 +93,38 @@ fi
 [[ -z $upx_exe && -f $upx_BUILDDIR/upx.out ]] && upx_exe=$upx_BUILDDIR/upx.out
 [[ -z $upx_exe && -f $upx_BUILDDIR/upx.exe ]] && upx_exe=$upx_BUILDDIR/upx.exe
 if [[ -z $upx_exe ]]; then exit 1; fi
+upx_run=$upx_exe
 if [[ $BM_T =~ (^|\+)qemu($|\+) && -n $upx_qemu ]]; then
-    upx_exe="$upx_qemu $upx_qemu_flags -- $upx_exe"
+    upx_run="$upx_qemu $upx_qemu_flags -- $upx_exe"
 fi
 if [[ $BM_T =~ (^|\+)wine($|\+) && -n $upx_wine ]]; then
-    upx_exe="$upx_wine $upx_wine_flags $upx_exe"
+    upx_run="$upx_wine $upx_wine_flags $upx_exe"
 fi
-if ! $upx_exe --version >/dev/null; then exit 1; fi
-
 if [[ $BM_T =~ (^|\+)valgrind($|\+) ]]; then
-    valgrind_flags="--leak-check=full --show-reachable=yes"
-    valgrind_flags="-q --leak-check=no --error-exitcode=1"
-    valgrind_flags="--leak-check=no --error-exitcode=1"
-    upx_exe="valgrind $valgrind_flags $upx_exe"
+    if [[ -z $upx_valgrind ]]; then
+        upx_valgrind="valgrind"
+    fi
+    if [[ -z $upx_valgrind_flags ]]; then
+        upx_valgrind_flags="--leak-check=full --show-reachable=yes"
+        upx_valgrind_flags="-q --leak-check=no --error-exitcode=1"
+        upx_valgrind_flags="--leak-check=no --error-exitcode=1"
+    fi
+    upx_run="$upx_valgrind $upx_valgrind_flags $upx_exe"
 fi
 
 if [[ $BM_B =~ (^|\+)coverage($|\+) ]]; then
     (cd / && cd $upx_BUILDDIR && lcov -d . --zerocounters)
 fi
 
-rm -rf ./testsuite_1
-mkdir testsuite_1
-cd testsuite_1
-
 export UPX=
 export UPX="--no-color --no-progress"
 
+# let's go
+if ! $upx_run --version >/dev/null; then exit 1; fi
+rm -rf ./testsuite_1
+mkbuilddirs testsuite_1
+cd testsuite_1 || exit 1
+
 
 # /***********************************************************************
 # // decompression tests
@@ -142,7 +148,7 @@ for f in $upx_testsuite_SRCDIR/files/packed/*/upx-3.91*; do
     testsuite_split_f $f
     [[ -z $fb ]] && continue
     mkdir -p $testdir/$fsubdir
-    $upx_exe -d $f -o $testdir/$fsubdir/$fb
+    $upx_run -d $f -o $testdir/$fsubdir/$fb
 done
 testsuite_check_sha $testdir
 
@@ -222,10 +228,21 @@ a647ed1aea16f58b544228279ad7159cd3ec5c3533efef1fd2df5a5a59b5d663 *i386-win32.pe/
 time testsuite_run_compress --all-methods --no-lzma --no-filter
 
 
+testsuite_header "UPX testsuite summary"
+echo "upx_exe='$upx_exe'"
+if [[ $upx_run != $upx_exe ]]; then
+    echo "upx_run='$upx_run'"
+fi
+if [[ -f $upx_exe ]]; then
+    ls -l "$upx_exe"
+    file "$upx_exe" || true
+fi
+echo "upx_testsuite_SRCDIR='$upx_testsuite_SRCDIR'"
+echo "upx_testsuite_BUILDDIR='$upx_testsuite_BUILDDIR'"
 echo
 if [[ $exit_code == 0 ]]; then
     echo "UPX testsuite passed. All done."
 else
-    echo "UPX-ERROR: UPX testsuite FAILED. See log file."
+    echo "UPX-ERROR: UPX testsuite FAILED with $num_errors error(s). See log file."
 fi
 exit $exit_code
diff --git a/.travis.yml b/.travis.yml
index f435b21a..adc80605 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -24,7 +24,7 @@ addons:
 
 env:
   global:
-    - C= B= CROSS= T=
+    - CROSS= C= B= T=
   matrix:
     - TRAVIS_EMPTY_JOB_WORKAROUND=true
 
@@ -140,19 +140,19 @@ matrix:
       addons: { apt: { sources: *S, packages: [ "clang-3.8" ] } }
     - os: linux
       compiler: gcc
-      env: C=gcc-4.6 CROSS=arm-linux-gnueabi T=SKIP
+      env: CROSS=arm-linux-gnueabi C=gcc-4.6 T=SKIP
       addons: { apt: { packages: [ "g++-arm-linux-gnueabi", "qemu-user" ] } }
     - os: linux
       compiler: gcc
-      env: C=gcc-4.6 CROSS=arm-linux-gnueabihf T=SKIP
+      env: CROSS=arm-linux-gnueabihf C=gcc-4.6 T=SKIP
       addons: { apt: { packages: [ "g++-arm-linux-gnueabihf", "qemu-user" ] } }
     - os: linux
       compiler: gcc
-      env: C=gcc-4.6 CROSS=i386-w64-mingw32 T=wine
+      env: CROSS=i386-w64-mingw32 C=gcc-4.6 T=wine
       addons: { apt: { packages: [ "binutils-mingw-w64-i686", "g++-mingw-w64-i686", "wine" ] } }
     - os: linux
       compiler: gcc
-      env: C=gcc-4.6 CROSS=x86_64-w64-mingw32 T=wine
+      env: CROSS=x86_64-w64-mingw32 C=gcc-4.6 T=wine
       addons: { apt: { packages: [ "binutils-mingw-w64-x86-64", "g++-mingw-w64-x86-64", "wine" ] } }
     - os: osx
       compiler: clang
diff --git a/src/Makefile b/src/Makefile
index 703c9597..8adb4aa9 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -85,7 +85,7 @@ compress_lzma$(objext) filteri$(objext) : CXXFLAGS := $(filter-out $(CXXFLAGS_SA
 endif
 
 
-all: upx$(exeext) | ./.depend
+all: check-whitespace upx$(exeext) | ./.depend
 .DELETE_ON_ERROR: upx$(exeext) $(upx_OBJECTS) ./.depend
 
 upx$(exeext): $(upx_OBJECTS) $(upx_DEPENDENCIES)
@@ -106,6 +106,11 @@ else
 .PHONY: ./.depend
 endif
 
+ifeq ($(shell uname),Linux)
+check-whitespace : ; bash $(top_srcdir)/src/stub/scripts/check_whitespace.sh $(top_srcdir)
+endif
+.PHONY: check-whitespace
+
 
 ./.depend compress_lzma$(objext) : INCLUDES += -I$(UPX_LZMADIR)
 
diff --git a/src/p_mach.cpp b/src/p_mach.cpp
index 0512f572..c8481dc5 100644
--- a/src/p_mach.cpp
+++ b/src/p_mach.cpp
@@ -2086,7 +2086,7 @@ int PackMachBase<T>::canUnpack()
             unsigned const *p;
             for (p = (unsigned const *)&buf[0x1000]; p > lo; ) if (*--p) {
                 overlay_offset  = *(TE32 const *)p;
-                if (overlay_offset < offLINK) {
+                if ((off_t)overlay_offset < offLINK) {
                     overlay_offset -= (char const *)p - (char const *)lo
                         + (offLINK - 0x1000) - sizeof(l_info);
                     fi->seek(overlay_offset, SEEK_SET);
@@ -2097,7 +2097,7 @@ int PackMachBase<T>::canUnpack()
                     }
                 }
             }
-            
+
             overlay_offset = 0;
         }
     }
diff --git a/src/stub/scripts/check_whitespace.sh b/src/stub/scripts/check_whitespace.sh
new file mode 100755
index 00000000..bffb987d
--- /dev/null
+++ b/src/stub/scripts/check_whitespace.sh
@@ -0,0 +1,33 @@
+#! /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
+
+find . \
+    -type d -name '.git' -prune -o \
+    -type d -name '.hg' -prune -o \
+    -type d -name 'build*' -prune -o \
+    -type d -name 'tmp*' -prune -o \
+    -type f -iname '*.bat' -prune -o \
+    -type f -iname '*.exe' -prune -o \
+    -type f -iname '*.pdf' -prune -o \
+    -type f -print0 | LC_ALL=C sort -z | \
+xargs -0r perl -n -e '
+    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