diff --git a/scripts/build.sh b/scripts/build.sh
index 4c02cedb3..5533cf939 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -1,6 +1,10 @@
 #!/usr/bin/env bash
-#
+
 # This script builds the application from source for multiple platforms.
+# Determine the arch/os combos we're building for
+ALL_XC_ARCH="386 amd64 arm arm64 ppc64le"
+ALL_XC_OS="linux darwin windows freebsd openbsd solaris"
+
 set -e
 
 # Get the parent directory of where this script is.
@@ -21,33 +25,82 @@ rm -f bin/*
 rm -rf pkg/*
 mkdir -p bin/
 
-OLDIFS=$IFS
-IFS=:
-case $(uname) in
-    MINGW*|MSYS*)
-        IFS=";"
+# helpers for Cygwin-hosted builds
+: ${OSTYPE:=`uname`}
+
+case $OSTYPE in
+    MINGW*|MSYS*|cygwin|CYGWIN*)
+        # cygwin only translates ';' to ':' on select environment variables
+        PATHSEP=';'
         ;;
+    *)	PATHSEP=':'
 esac
 
+function convert_path() {
+    local flag
+    [ "${1:0:1}" = '-' ] && { flag="$1"; shift; }
+
+    [ -n "$1" ] || return 0
+    case ${OSTYPE:-`uname`} in
+        cygwin|CYGWIN*)
+            cygpath $flag -- "$1"
+            ;;
+        *)  echo "$1"
+    esac
+}
+
+# XXX works in MINGW?
+which go &>/dev/null || PATH+=":`convert_path "${GOROOT:?}"`/bin"
+
+OLDIFS="$IFS"
+
+# make sure GOPATH is consistent - Windows binaries can't handle Cygwin-style paths
+IFS="$PATHSEP"
+for d in ${GOPATH:-$(go env GOPATH)}; do
+    _GOPATH+="${_GOPATH:+$PATHSEP}$(convert_path --windows "$d")"
+done
+GOPATH="$_GOPATH"
+
+# locate 'gox' and traverse GOPATH if needed
+which "${GOX:=gox}" &>/dev/null || {
+    for d in $GOPATH; do
+        GOX="$(convert_path --unix "$d")/bin/gox"
+        [ -x "$GOX" ] && break || unset GOX
+    done
+}
+IFS="$OLDIFS"
+
 # Build!
 echo "==> Building..."
+
+# If in dev mode, only build for ourself
+if [ -n "${PACKER_DEV+x}" ]; then
+    XC_OS=$(go env GOOS)
+    XC_ARCH=$(go env GOARCH)
+fi
+
 set +e
-${GOX:-$GOPATH/bin/gox} \
-    -os="${XC_OS}" \
-    -arch="${XC_ARCH}" \
+${GOX:?command not found} \
+    -os="${XC_OS:-$ALL_XC_OS}" \
+    -arch="${XC_ARCH:-$ALL_XC_ARCH}" \
     -osarch="!darwin/arm !darwin/arm64" \
     -ldflags "${GOLDFLAGS}" \
     -output "pkg/{{.OS}}_{{.Arch}}/packer" \
     .
+set -e
 
+# trim GOPATH to first element
+IFS="$PATHSEP"
+MAIN_GOPATH=($GOPATH)
+MAIN_GOPATH="$(convert_path --unix "$MAIN_GOPATH")"
 IFS=$OLDIFS
-set -e
 
 # Copy our OS/Arch to the bin/ directory
 echo "==> Copying binaries for this platform..."
-for F in $(find pkg/$(go env GOOS)_$(go env GOARCH) -mindepth 1 -maxdepth 1 -type f); do
+DEV_PLATFORM="./pkg/$(go env GOOS)_$(go env GOARCH)"
+for F in $(find ${DEV_PLATFORM} -mindepth 1 -maxdepth 1 -type f); do
     cp -v ${F} bin/
-    cp -v ${F} ${GOPATH}/bin/
+    cp -v ${F} ${MAIN_GOPATH}/bin/
 done
 
 # Done!