diff --git a/etc/scripts/build-external-libs/boost/fetch.sh b/etc/scripts/build-external-libs/boost/fetch.sh
index 24c9ea6..8a68690 100755
--- a/etc/scripts/build-external-libs/boost/fetch.sh
+++ b/etc/scripts/build-external-libs/boost/fetch.sh
@@ -44,7 +44,7 @@ out=${name}_${version}.tar.bz2
 
 rm -rf ${name}_${version}
 
-if [ -f $SRC_BOOST ]; then
+if [ ! -z $SRC_BOOST ]; then
     echo "using pre-fetched $name"
     cp $SRC_BOOST  $out
 else
diff --git a/etc/scripts/build-external-libs/iconv/fetch.sh b/etc/scripts/build-external-libs/iconv/fetch.sh
index 1ed1bc8..fe65176 100755
--- a/etc/scripts/build-external-libs/iconv/fetch.sh
+++ b/etc/scripts/build-external-libs/iconv/fetch.sh
@@ -43,7 +43,7 @@ out=${name}-${version}.tar.gz
 
 rm -rf ${name}-${version}
 
-if [ -f $SRC_ICONV ]; then
+if [ ! -z $SRC_ICONV ]; then
     echo "using pre-fetched $name"
     cp $SRC_ICONV  $out
 else
diff --git a/etc/scripts/build-external-libs/openssl/fetch.sh b/etc/scripts/build-external-libs/openssl/fetch.sh
index bae8fb1..2584b9b 100755
--- a/etc/scripts/build-external-libs/openssl/fetch.sh
+++ b/etc/scripts/build-external-libs/openssl/fetch.sh
@@ -43,7 +43,7 @@ out=openssl-${version}.tar.gz
 
 rm -rf ${name}-${version}
 
-if [ -f $SRC_OPENSSL ]; then
+if [ ! -z $SRC_OPENSSL ]; then
     echo "using pre-fetched $name"
     cp $SRC_OPENSSL $out
 else
diff --git a/etc/scripts/build-external-libs/sodium/fetch.sh b/etc/scripts/build-external-libs/sodium/fetch.sh
index 10bcfff..b8402a9 100755
--- a/etc/scripts/build-external-libs/sodium/fetch.sh
+++ b/etc/scripts/build-external-libs/sodium/fetch.sh
@@ -43,7 +43,7 @@ out=${name}-${version}.tar.gz
 
 rm -rf ${name}-${version}
 
-if [ -f $SRC_SODIUM ]; then
+if [ ! -z $SRC_SODIUM ]; then
     echo "using pre-fetched $name"
     cp $SRC_SODIUM  $out
 else
diff --git a/etc/scripts/build-external-libs/wownero/fetch.sh b/etc/scripts/build-external-libs/wownero/fetch.sh
index 24b78b0..bf0ad08 100755
--- a/etc/scripts/build-external-libs/wownero/fetch.sh
+++ b/etc/scripts/build-external-libs/wownero/fetch.sh
@@ -45,39 +45,40 @@ chmod u+w -f -R $out || true
 
 rm -rf $out
 
-if [ -d $SRC_WOWNERO_DIR ]; then
+if [ ! -z $SRC_WOWNERO_DIR ]; then
     echo "using pre-fetched $name"
     rsync -av --no-perms --no-owner --no-group --delete $SRC_WOWNERO_DIR/* $out
     chmod u+w -R $out/external
+    cd $name
 else
     git clone --depth 1 https://github.com/wownero/wownero.git -b $version
+    cd $name
     test `git rev-parse HEAD` = $githash || exit 1
 fi
 
-cd $name
 
-if [ -d $SRC_MINIUPNP_DIR ]; then
+if [ ! -z $SRC_MINIUPNP_DIR ]; then
     echo "using pre-fetched miniupnpc"
     rsync -av --no-perms --no-owner --no-group --delete $SRC_MINIUPNP_DIR/* external/miniupnp
 else
     git submodule update --init external/miniupnp
 fi
 
-if [ -d $SRC_RAPIDJSON_DIR ]; then
+if [ ! -z $SRC_RAPIDJSON_DIR ]; then
     echo "using pre-fetched rapidjson"
     rsync -av --no-perms --no-owner --no-group --delete $SRC_RAPIDJSON_DIR/* external/rapidjson
 else
     git submodule update --init external/rapidjson
 fi
 
-if [ -f $SRC_RANDOMWOW ]; then
+if [ ! -z $SRC_RANDOMWOW ]; then
     echo "using pre-fetched RandomWOW"
     tar xzf $SRC_RANDOMWOW -C external/RandomWOW --strip-components=1
 else
     git submodule update --init external/RandomWOW
 fi
 
-if [ -d $SRC_UNBOUND_DIR ]; then
+if [ ! -z $SRC_UNBOUND_DIR ]; then
     echo "using pre-fetched unbound"
     rsync -av --no-perms --no-owner --no-group --delete $SRC_UNBOUND_DIR/* external/unbound
 else