diff --git a/config/nim.cfg b/config/nim.cfg
index aa652c1ee0f..144c644bd81 100644
--- a/config/nim.cfg
+++ b/config/nim.cfg
@@ -311,12 +311,6 @@ tcc.options.always = "-w"
   --define:nimEmulateOverflowChecks
 @end
 
-@if nimv019:
-  --multimethods:on
-  --define:nimOldCaseObjects
-  --define:nimOldShiftRight
-@end
-
 @if lto or lto_incremental:
   @if lto_incremental:
    vcc.options.always%= "${vcc.options.always} /GL /Gw /Gy"
diff --git a/lib/system/assign.nim b/lib/system/assign.nim
index a49d9c9e9bb..7baf4e1a0f7 100644
--- a/lib/system/assign.nim
+++ b/lib/system/assign.nim
@@ -293,12 +293,5 @@ proc FieldDiscriminantCheck(oldDiscVal, newDiscVal: int,
                             L: int) {.compilerproc.} =
   let oldBranch = selectBranch(oldDiscVal, L, a)
   let newBranch = selectBranch(newDiscVal, L, a)
-  when defined(nimOldCaseObjects):
-    if newBranch != oldBranch and oldDiscVal != 0:
-      sysFatal(FieldDefect, "assignment to discriminant changes object branch")
-  else:
-    if newBranch != oldBranch:
-      if oldDiscVal != 0:
-        sysFatal(FieldDefect, "assignment to discriminant changes object branch")
-      else:
-        sysFatal(FieldDefect, "assignment to discriminant changes object branch; compile with -d:nimOldCaseObjects for a transition period")
+  if newBranch != oldBranch:
+    sysFatal(FieldDefect, "assignment to discriminant changes object branch")