diff --git a/ffmpeg.nu b/ffmpeg.nu
index ad38d15..6b31924 100644
--- a/ffmpeg.nu
+++ b/ffmpeg.nu
@@ -101,7 +101,7 @@ def "filterchain to-string" []: table -> string {
   $in | each { filter to-string }| str join ','
 }
 
-def "filter to-string" []: record<input: list<string> name: string params: table<param: string value: string> output: list<string>> -> string {
+def "filter to-string" []: record<input: list<string> name: string params: table<param: string value: any> output: list<string>> -> string {
   $in | update input {
     str join ']['
   } | update output {
@@ -162,7 +162,7 @@ export def complex-filter [
   --output (-o): list<string> = []
   name: string
   params: record = {}
-]: nothing -> record<input: list<string> name: string params: table<param: string, value: string> output: list<string>> {
+]: nothing -> record<input: list<string> name: string params: table<param: string, value: any> output: list<string>> {
   {
     input: $input
     name: $name
diff --git a/filters.nu b/filters.nu
index f3f1ed1..b783962 100755
--- a/filters.nu
+++ b/filters.nu
@@ -91,8 +91,8 @@ export def format [
   ] {
   (append-complex-filter format {
     pix_fmts: ($pix_fmts | list to-pipe-separated-string)
-    color_spaces: ($color_spaces | list to-pipe-separated-string)
-    color_ranges: ($color_ranges | list to-pipe-separated-string)
+    color_spaces: ($color_spaces | default [] | list to-pipe-separated-string)
+    color_ranges: ($color_ranges | default [] | list to-pipe-separated-string)
   } -i $input -o $output)
 }