diff --git a/src/awesomewm.d.tl/entity/Function_Info.tl b/src/awesomewm.d.tl/entity/Function_Info.tl
index d3e3478..534da92 100644
--- a/src/awesomewm.d.tl/entity/Function_Info.tl
+++ b/src/awesomewm.d.tl/entity/Function_Info.tl
@@ -18,7 +18,7 @@ local record Function_Info
    parameters: List<Variable_Info.Variable_Info>
    return_types: List<Type_Info.Type_Info>
 
-   append_parameter: function(self: Function_Info, name: string, type: string)
+   append_parameter: function(self: Function_Info, name: string, types: List<Type_Info.Type_Info>)
    append_return_type: function(self: Function_Info, return_type: string)
 
    fixup: function(Function_Info)
diff --git a/src/awesomewm.d.tl/entity/Variable_Info.tl b/src/awesomewm.d.tl/entity/Variable_Info.tl
index 03f169e..c0c5fea 100644
--- a/src/awesomewm.d.tl/entity/Variable_Info.tl
+++ b/src/awesomewm.d.tl/entity/Variable_Info.tl
@@ -16,11 +16,9 @@ end
 
 local __Variable_Info: metatable<Variable_Info> = {
    __call = function(_self: Variable_Info, name: string | nil, types: List<Type_Info.Type_Info> | nil): Variable_Info
-      name = name or ""
-      types = types or List()
       return {
-         name = name,
-         types = types,
+         name = name or "",
+         types = types or List(),
 
          fixup = function(self: Variable_Info)
             for t in self.types:iter() do
diff --git a/src/awesomewm.d.tl/generator/snippets.tl b/src/awesomewm.d.tl/generator/snippets.tl
index 7d3209b..5060836 100644
--- a/src/awesomewm.d.tl/generator/snippets.tl
+++ b/src/awesomewm.d.tl/generator/snippets.tl
@@ -30,7 +30,7 @@ end
 function snippets.render_requires(requires: Map<string, string>): string
    local tmpl = [[local $(name) = require "$(path)"]]
 
-   local require_statements <const> = List()
+   local require_statements <const>: List<string> = List()
    for name, path in requires:iter() do
       local tmpl_args = {
          name = name,
diff --git a/src/awesomewm.d.tl/utils.tl b/src/awesomewm.d.tl/utils.tl
index a0453a5..828070e 100644
--- a/src/awesomewm.d.tl/utils.tl
+++ b/src/awesomewm.d.tl/utils.tl
@@ -58,12 +58,12 @@ function utils.do_or_fail<T>(func: function<T>(...: any): (T | nil, string), ...
 
    local ok, res, err = pcall(func, ...)
 
-   if not (ok and res) then
+   if not ok then
       log:error(logger.message_with_metadata("do_or_fail failed!", { error = err }))
       error(err)
    end
 
-   return res
+   return res as T -- promote to T since pcall succeeded at this point
 end
 
 return utils