diff --git a/compiler/liftdestructors.nim b/compiler/liftdestructors.nim
index 0f78d5c1c7..e5d3a39d09 100644
--- a/compiler/liftdestructors.nim
+++ b/compiler/liftdestructors.nim
@@ -748,12 +748,19 @@ proc atomicRefOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
 
   # YRC uses dedicated runtime procs for the entire write barrier:
   if c.g.config.selectedGC == gcYrc:
+    let desc =
+      if isFinal(elemType):
+        let ti = genBuiltin(c, mGetTypeInfoV2, "getTypeInfoV2", newNodeIT(nkType, x.info, elemType))
+        ti.typ = getSysType(c.g, c.info, tyPointer)
+        ti
+      else:
+        newNodeIT(nkNilLit, c.info, getSysType(c.g, c.info, tyPointer))
     case c.kind
     of attachedAsgn, attachedDup:
-      body.add callCodegenProc(c.g, "nimAsgnYrc", c.info, genAddr(c, x), y)
+      body.add callCodegenProc(c.g, "nimAsgnYrc", c.info, genAddr(c, x), y, desc)
       return
     of attachedSink:
-      body.add callCodegenProc(c.g, "nimSinkYrc", c.info, genAddr(c, x), y)
+      body.add callCodegenProc(c.g, "nimSinkYrc", c.info, genAddr(c, x), y, desc)
       return
     else: discard # fall through for destructor, trace, wasMoved
 
@@ -842,13 +849,15 @@ proc atomicClosureOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
   xenv.typ = getSysType(c.g, c.info, tyPointer)
 
   # YRC uses dedicated runtime procs for the write barrier on the env pointer:
+  # Closure envs are always polymorphic, so pass nil for desc (uses Dyn variant):
   if c.g.config.selectedGC == gcYrc:
+    let nilDesc = newNodeIT(nkNilLit, c.info, getSysType(c.g, c.info, tyPointer))
     case c.kind
     of attachedAsgn, attachedDup:
-      body.add callCodegenProc(c.g, "nimAsgnYrc", c.info, genAddr(c, xenv), y)
+      body.add callCodegenProc(c.g, "nimAsgnYrc", c.info, genAddr(c, xenv), y, nilDesc)
       return
     of attachedSink:
-      body.add callCodegenProc(c.g, "nimSinkYrc", c.info, genAddr(c, xenv), y)
+      body.add callCodegenProc(c.g, "nimSinkYrc", c.info, genAddr(c, xenv), y, nilDesc)
       return
     else: discard # fall through for destructor, trace, wasMoved
 
diff --git a/lib/system/yrc.nim b/lib/system/yrc.nim
index bd981f51be..b2225a565c 100644
--- a/lib/system/yrc.nim
+++ b/lib/system/yrc.nim
@@ -390,7 +390,7 @@ proc GC_partialCollect*(limit: int) =
       roots.len = limit
 
 proc GC_fullCollect* =
-  collectCycles()
+  GC_runOrc()
 
 proc GC_enableMarkAndSweep*() = GC_enableOrc()
 proc GC_disableMarkAndSweep*() = GC_disableOrc()
@@ -448,7 +448,13 @@ proc unsureAsgnRef(dest: ptr pointer, src: pointer) {.inline.} =
   dest[] = src
   if src != nil: nimIncRefCyclic(src, true)
 
-proc nimAsgnYrc(dest: ptr pointer; src: pointer) {.compilerRtl.} =
+proc yrcDec(tmp: pointer; desc: PNimTypeV2) {.inline.} =
+  if desc != nil:
+    discard nimDecRefIsLastCyclicStatic(tmp, desc)
+  else:
+    discard nimDecRefIsLastCyclicDyn(tmp)
+
+proc nimAsgnYrc(dest: ptr pointer; src: pointer; desc: PNimTypeV2) {.compilerRtl.} =
   ## YRC write barrier for ref copy assignment.
   ## Atomically stores src into dest, then buffers RC adjustments.
   ## Freeing is always done by the cycle collector, never inline.
@@ -457,15 +463,15 @@ proc nimAsgnYrc(dest: ptr pointer; src: pointer) {.compilerRtl.} =
   if src != nil:
     nimIncRefCyclic(src, true)
   if tmp != nil:
-    discard nimDecRefIsLastCyclicDyn(tmp)
+    yrcDec(tmp, desc)
 
-proc nimSinkYrc(dest: ptr pointer; src: pointer) {.compilerRtl.} =
+proc nimSinkYrc(dest: ptr pointer; src: pointer; desc: PNimTypeV2) {.compilerRtl.} =
   ## YRC write barrier for ref sink (move). No incRef on source.
   ## Freeing is always done by the cycle collector, never inline.
   let tmp = dest[]
   atomicStoreN(dest, src, ATOMIC_RELEASE)
   if tmp != nil:
-    discard nimDecRefIsLastCyclicDyn(tmp)
+    yrcDec(tmp, desc)
 
 proc nimMarkCyclic(p: pointer) {.compilerRtl, inl.} =
   when optimizedOrc: