diff --git a/lib/options.nix b/lib/options.nix
index 4cc16dac..bc115eda 100644
--- a/lib/options.nix
+++ b/lib/options.nix
@@ -167,6 +167,8 @@ rec {
 
       mkNum' = args: mkNullableWithRaw' (args // { type = types.number; });
       mkNum = pluginDefault: description: mkNum' { inherit pluginDefault description; };
+      mkProportion' = args: mkNullableWithRaw' (args // { type = types.numbers.between 0.0 1.0; });
+      mkProportion = pluginDefault: description: mkProportion' { inherit pluginDefault description; };
       mkInt' = args: mkNullableWithRaw' (args // { type = types.int; });
       mkInt = pluginDefault: description: mkNum' { inherit pluginDefault description; };
       # Positive: >0