diff --git a/astronaut/astronaut b/astronaut/astronaut
index 08af699..ee6e3af 100755
--- a/astronaut/astronaut
+++ b/astronaut/astronaut
@@ -161,7 +161,7 @@ safe_sed() {
 download() {
     mkdir -p "$dir_source/$name"
 
-    local filename="$(basename $(echo "$1" | cut -d? -f1))"
+    [ "$3" ] && local filename="$3" || local filename="$(basename $(echo "$1" | cut -d? -f1))"
     local path="$dir_source/$name/$filename"
 
     [ "$2" -a -f "$path" ] && local checksum="$(_mksum "$path")"
@@ -169,7 +169,7 @@ download() {
     if [ ! -e "$path" -o "$checksum" != "$2" ]; then
         _msg "Downloading $filename"
 
-        [ "$3" ] && local cmd="$3" || local cmd="$cmd_download"
+        [ "$4" ] && local cmd="$4" || local cmd="$cmd_download"
         eval $(echo "$cmd" | sed -e "s/{dst}/'$(safe_sed "$path")'/g" -e "s/{src}/'$(safe_sed "$1")'/g")
 
         checksum="$(_mksum "$path")"
diff --git a/astronaut/examples/hello.sat b/astronaut/examples/hello.sat
index a3eef67..9e9dfec 100644
--- a/astronaut/examples/hello.sat
+++ b/astronaut/examples/hello.sat
@@ -44,9 +44,10 @@ define_option 'test=Default value'  # It is also allowed to provide no descripti
 # - options
 
 # Get them files.
-# URL [REQUIRED], MD5sum, Custom command
+# URL [REQUIRED], MD5sum, Custom filename, Custom command
 download "https://ftp.gnu.org/gnu/$name/$name-$version.tar.gz" \
          '6cd0ffea3884a4e79330338dcc2987d6' \
+         "$name-$version.tar.gz" \
          'curl -L -o {dst} {src}'
 
 # Abbreviation download and extract. Does not allow custom commands.