diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go
index 30f2a4fca5..3f437bc02f 100644
--- a/src/runtime/malloc.go
+++ b/src/runtime/malloc.go
@@ -655,6 +655,7 @@ func mallocgc(size uintptr, typ *_type, needzero bool) unsafe.Pointer {
 		size = s.elemsize
 	}
 
+	var scanSize uintptr
 	if noscan {
 		// All objects are pre-marked as noscan. Nothing to do.
 	} else {
@@ -673,11 +674,12 @@ func mallocgc(size uintptr, typ *_type, needzero bool) unsafe.Pointer {
 			// pointers, GC has to scan to the last
 			// element.
 			if typ.ptrdata != 0 {
-				c.local_scan += dataSize - typ.size + typ.ptrdata
+				scanSize = dataSize - typ.size + typ.ptrdata
 			}
 		} else {
-			c.local_scan += typ.ptrdata
+			scanSize = typ.ptrdata
 		}
+		c.local_scan += scanSize
 
 		// Ensure that the stores above that initialize x to
 		// type-safe memory and set the heap bits occur before
@@ -694,7 +696,7 @@ func mallocgc(size uintptr, typ *_type, needzero bool) unsafe.Pointer {
 	// a race marking the bit.
 	if gcphase == _GCmarktermination || gcBlackenPromptly {
 		systemstack(func() {
-			gcmarknewobject_m(uintptr(x), size)
+			gcmarknewobject_m(uintptr(x), size, scanSize)
 		})
 	}
 
diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go
index 1c184db10b..d120dae05a 100644
--- a/src/runtime/mgc.go
+++ b/src/runtime/mgc.go
@@ -304,7 +304,8 @@ type gcControllerState struct {
 	// scanWork is the total scan work performed this cycle. This
 	// is updated atomically during the cycle. Updates occur in
 	// bounded batches, since it is both written and read
-	// throughout the cycle.
+	// throughout the cycle. At the end of the cycle, this is how
+	// much of the retained heap is scannable.
 	//
 	// Currently this is the bytes of heap scanned. For most uses,
 	// this is an opaque unit of work, but for estimation the
@@ -1578,9 +1579,13 @@ func gcMark(start_time int64) {
 	work.markrootDone = true
 
 	for i := 0; i < int(gomaxprocs); i++ {
-		if !allp[i].gcw.empty() {
+		gcw := &allp[i].gcw
+		if !gcw.empty() {
 			throw("P has cached GC work at end of mark termination")
 		}
+		if gcw.scanWork != 0 || gcw.bytesMarked != 0 {
+			throw("P has unflushed stats at end of mark termination")
+		}
 	}
 
 	if trace.enabled {
diff --git a/src/runtime/mgcmark.go b/src/runtime/mgcmark.go
index 1ab8315a29..0d05838987 100644
--- a/src/runtime/mgcmark.go
+++ b/src/runtime/mgcmark.go
@@ -1134,12 +1134,14 @@ func gcDumpObject(label string, obj, off uintptr) {
 
 // If gcBlackenPromptly is true we are in the second mark phase phase so we allocate black.
 //go:nowritebarrier
-func gcmarknewobject_m(obj, size uintptr) {
+func gcmarknewobject_m(obj, size, scanSize uintptr) {
 	if useCheckmark && !gcBlackenPromptly { // The world should be stopped so this should not happen.
 		throw("gcmarknewobject called while doing checkmark")
 	}
 	heapBitsForAddr(obj).setMarked()
 	atomic.Xadd64(&work.bytesMarked, int64(size))
+	gcw := &getg().m.p.ptr().gcw
+	gcw.scanWork += int64(scanSize)
 }
 
 // Checkmarking