diff --git a/src/Fable.Python.fsproj b/src/Fable.Python.fsproj
index 213a444..a1e41a5 100644
--- a/src/Fable.Python.fsproj
+++ b/src/Fable.Python.fsproj
@@ -12,10 +12,12 @@
     <Compile Include="stdlib/Ast.fs" />
     <Compile Include="stdlib/Builtins.fs" />
     <Compile Include="stdlib/Json.fs" />
+    <Compile Include="stdlib/Math.fs" />
     <Compile Include="stdlib/Os.fs" />
-    <Compile Include="stdlib/TkInter.fs" />
     <Compile Include="stdlib/Queue.fs" />
-    <Compile Include="stdlib/Math.fs" />
+    <Compile Include="stdlib/Sys.fs" />
+    <Compile Include="stdlib/Time.fs" />
+    <Compile Include="stdlib/TkInter.fs" />
 
     <Compile Include="cognite-sdk/CogniteSdk.fs" />
     <Compile Include="flask/Flask.fs" />
diff --git a/src/stdlib/Os.fs b/src/stdlib/Os.fs
index 70133d5..1e14d6c 100644
--- a/src/stdlib/Os.fs
+++ b/src/stdlib/Os.fs
@@ -1,14 +1,22 @@
 module Fable.Python.Os
 
+open System.Collections.Generic
 open Fable.Core
 
 // fsharplint:disable MemberNames
 
 type IExports =
+    abstract chdir : string -> unit
+    abstract chroot : string -> unit
+    abstract close : fd: int -> unit
+    abstract environ : Dictionary<string, string>
+    abstract getcwd : unit -> string
     abstract getenv : key: string -> string option
     abstract getenv : key: string * ``default``: string -> string
+    abstract kill : pid: int * ``sig``: int -> unit
     abstract putenv : key: string * value: string -> unit
 
 
+/// Miscellaneous operating system interfaces
 [<ImportAll("os")>]
 let os: IExports = nativeOnly
diff --git a/src/stdlib/Sys.fs b/src/stdlib/Sys.fs
new file mode 100644
index 0000000..36c16cb
--- /dev/null
+++ b/src/stdlib/Sys.fs
@@ -0,0 +1,33 @@
+module Fable.Python.Sys
+
+open Fable.Core
+
+// fsharplint:disable MemberNames
+
+[<StringEnum>]
+type ByteOrder =
+    | Little
+    | Big
+
+type VersionInfo =
+    abstract major : int
+    abstract minor: int
+    abstract micro: int
+    abstract releaselevel: string
+    abstract serial: int
+
+type IExports =
+    abstract argv : string array
+    abstract byteorder: ByteOrder
+    abstract hexversion: int
+    abstract maxsize: int
+    abstract maxunicode: int
+    abstract path : string array
+    abstract platform : string
+    abstract prefix: string
+    abstract version: string
+    abstract version_info: VersionInfo
+
+/// System-specific parameters and functions
+[<ImportAll("sys")>]
+let sys: IExports = nativeOnly
diff --git a/src/stdlib/Time.fs b/src/stdlib/Time.fs
new file mode 100644
index 0000000..e682a1b
--- /dev/null
+++ b/src/stdlib/Time.fs
@@ -0,0 +1,22 @@
+module Fable.Python.Time
+
+open Fable.Core
+
+// fsharplint:disable MemberNames
+
+type IExports =
+    abstract altzone : int
+    abstract ctime : unit -> string
+    abstract ctime : float -> string
+    abstract daylight : int
+    abstract monotonic : unit -> float
+    abstract perf_counter : unit -> float
+    abstract process_time : unit -> float
+    abstract sleep : secs: float -> unit
+    abstract time : unit -> float
+    abstract timezone : int
+    abstract tzname : string * string
+
+/// Time access and conversions
+[<ImportAll("time")>]
+let time: IExports = nativeOnly