diff --git a/compiler/scriptconfig.nim b/compiler/scriptconfig.nim
index bfff864797..e3a9478d13 100644
--- a/compiler/scriptconfig.nim
+++ b/compiler/scriptconfig.nim
@@ -63,8 +63,10 @@ proc setupVM*(module: PSym; cache: IdentCache; scriptName: string;
     os.removeFile getString(a, 0)
   cbos createDir:
     os.createDir getString(a, 0)
-  cbos getOsError:
-    setResult(a, errorMsg)
+
+  result.registerCallback "stdlib.system.getOsError",
+    proc (a: VmArgs) = setResult(a, errorMsg)
+
   cbos setCurrentDir:
     os.setCurrentDir getString(a, 0)
   cbos getCurrentDir:
diff --git a/tools/kochdocs.nim b/tools/kochdocs.nim
index 3d146188fa..68662bab24 100644
--- a/tools/kochdocs.nim
+++ b/tools/kochdocs.nim
@@ -56,12 +56,8 @@ proc nimexec*(cmd: string) =
   exec findNim() & " " & cmd
 
 proc nimCompile*(input: string, outputDir = "bin", mode = "c", options = "") =
-  # TODO: simplify pending https://github.com/nim-lang/Nim/issues/9513
-  var cmd = findNim() & " " & mode
   let output = outputDir / input.splitFile.name.exe
-  cmd.add " -o:" & output
-  cmd.add " " & options
-  cmd.add " " & input
+  let cmd = findNim() & " " & mode & " -o:" & output & " " & options & " " & input
   exec cmd
 
 const