diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go
index 51c3625c3d..fbfaae0f93 100644
--- a/src/runtime/mbitmap.go
+++ b/src/runtime/mbitmap.go
@@ -1868,12 +1868,12 @@ func materializeGCProg(ptrdata uintptr, prog *byte) *mspan {
 	bitmapBytes := divRoundUp(ptrdata, 8*sys.PtrSize)
 	// Compute the number of pages needed for bitmapBytes.
 	pages := divRoundUp(bitmapBytes, pageSize)
-	s := mheap_.allocManual(pages, &memstats.gc_sys)
+	s := mheap_.allocManual(pages, spanAllocPtrScalarBits)
 	runGCProg(addb(prog, 4), nil, (*byte)(unsafe.Pointer(s.startAddr)), 1)
 	return s
 }
 func dematerializeGCProg(s *mspan) {
-	mheap_.freeManual(s, &memstats.gc_sys)
+	mheap_.freeManual(s, spanAllocPtrScalarBits)
 }
 
 func dumpGCProg(p *byte) {
diff --git a/src/runtime/mgcwork.go b/src/runtime/mgcwork.go
index 51e0fe9219..b3a068661e 100644
--- a/src/runtime/mgcwork.go
+++ b/src/runtime/mgcwork.go
@@ -371,7 +371,7 @@ func getempty() *workbuf {
 		}
 		if s == nil {
 			systemstack(func() {
-				s = mheap_.allocManual(workbufAlloc/pageSize, &memstats.gc_sys)
+				s = mheap_.allocManual(workbufAlloc/pageSize, spanAllocWorkBuf)
 			})
 			if s == nil {
 				throw("out of memory")
@@ -473,7 +473,7 @@ func freeSomeWbufs(preemptible bool) bool {
 				break
 			}
 			work.wbufSpans.free.remove(span)
-			mheap_.freeManual(span, &memstats.gc_sys)
+			mheap_.freeManual(span, spanAllocWorkBuf)
 		}
 	})
 	more := !work.wbufSpans.free.isEmpty()
diff --git a/src/runtime/mheap.go b/src/runtime/mheap.go
index 40fd58b0ef..df659e222b 100644
--- a/src/runtime/mheap.go
+++ b/src/runtime/mheap.go
@@ -861,6 +861,22 @@ func (h *mheap) reclaimChunk(arenas []arenaIdx, pageIdx, n uintptr) uintptr {
 	return nFreed
 }
 
+// spanAllocType represents the type of allocation to make, or
+// the type of allocation to be freed.
+type spanAllocType uint8
+
+const (
+	spanAllocHeap          spanAllocType = iota // heap span
+	spanAllocStack                              // stack span
+	spanAllocPtrScalarBits                      // unrolled GC prog bitmap span
+	spanAllocWorkBuf                            // work buf span
+)
+
+// manual returns true if the span allocation is manually managed.
+func (s spanAllocType) manual() bool {
+	return s != spanAllocHeap
+}
+
 // alloc allocates a new span of npage pages from the GC'd heap.
 //
 // spanclass indicates the span's size class and scannability.
@@ -877,7 +893,7 @@ func (h *mheap) alloc(npages uintptr, spanclass spanClass, needzero bool) *mspan
 		if h.sweepdone == 0 {
 			h.reclaim(npages)
 		}
-		s = h.allocSpan(npages, false, spanclass, &memstats.heap_inuse)
+		s = h.allocSpan(npages, spanAllocHeap, spanclass)
 	})
 
 	if s != nil {
@@ -902,9 +918,15 @@ func (h *mheap) alloc(npages uintptr, spanclass spanClass, needzero bool) *mspan
 // allocManual must be called on the system stack because it may
 // acquire the heap lock via allocSpan. See mheap for details.
 //
+// If new code is written to call allocManual, do NOT use an
+// existing spanAllocType value and instead declare a new one.
+//
 //go:systemstack
-func (h *mheap) allocManual(npages uintptr, stat *uint64) *mspan {
-	return h.allocSpan(npages, true, 0, stat)
+func (h *mheap) allocManual(npages uintptr, typ spanAllocType) *mspan {
+	if !typ.manual() {
+		throw("manual span allocation called with non-manually-managed type")
+	}
+	return h.allocSpan(npages, typ, 0)
 }
 
 // setSpans modifies the span map so [spanOf(base), spanOf(base+npage*pageSize))
@@ -1066,7 +1088,7 @@ func (h *mheap) freeMSpanLocked(s *mspan) {
 
 // allocSpan allocates an mspan which owns npages worth of memory.
 //
-// If manual == false, allocSpan allocates a heap span of class spanclass
+// If typ.manual() == false, allocSpan allocates a heap span of class spanclass
 // and updates heap accounting. If manual == true, allocSpan allocates a
 // manually-managed span (spanclass is ignored), and the caller is
 // responsible for any accounting related to its use of the span. Either
@@ -1081,7 +1103,7 @@ func (h *mheap) freeMSpanLocked(s *mspan) {
 // the heap lock and because it must block GC transitions.
 //
 //go:systemstack
-func (h *mheap) allocSpan(npages uintptr, manual bool, spanclass spanClass, sysStat *uint64) (s *mspan) {
+func (h *mheap) allocSpan(npages uintptr, typ spanAllocType, spanclass spanClass) (s *mspan) {
 	// Function-global state.
 	gp := getg()
 	base, scav := uintptr(0), uintptr(0)
@@ -1143,12 +1165,10 @@ HaveSpan:
 		s.needzero = 1
 	}
 	nbytes := npages * pageSize
-	if manual {
+	if typ.manual() {
 		s.manualFreeList = 0
 		s.nelems = 0
 		s.limit = s.base() + s.npages*pageSize
-		// Manually managed memory doesn't count toward heap_sys.
-		mSysStatDec(&memstats.heap_sys, s.npages*pageSize)
 		s.state.set(mSpanManual)
 	} else {
 		// We must set span properties before the span is published anywhere
@@ -1205,7 +1225,18 @@ HaveSpan:
 		mSysStatDec(&memstats.heap_released, scav)
 	}
 	// Update stats.
-	mSysStatInc(sysStat, nbytes)
+	switch typ {
+	case spanAllocHeap:
+		mSysStatInc(&memstats.heap_inuse, nbytes)
+	case spanAllocStack:
+		mSysStatInc(&memstats.stacks_inuse, nbytes)
+	case spanAllocPtrScalarBits, spanAllocWorkBuf:
+		mSysStatInc(&memstats.gc_sys, nbytes)
+	}
+	if typ.manual() {
+		// Manually managed memory doesn't count toward heap_sys.
+		mSysStatDec(&memstats.heap_sys, nbytes)
+	}
 	mSysStatDec(&memstats.heap_idle, nbytes)
 
 	// Publish the span in various locations.
@@ -1217,7 +1248,7 @@ HaveSpan:
 	// before that happens) or pageInUse is updated.
 	h.setSpans(s.base(), npages, s)
 
-	if !manual {
+	if !typ.manual() {
 		// Mark in-use span in arena page bitmap.
 		//
 		// This publishes the span to the page sweeper, so
@@ -1323,13 +1354,13 @@ func (h *mheap) freeSpan(s *mspan) {
 			bytes := s.npages << _PageShift
 			msanfree(base, bytes)
 		}
-		h.freeSpanLocked(s, true, true)
+		h.freeSpanLocked(s, spanAllocHeap)
 		unlock(&h.lock)
 	})
 }
 
 // freeManual frees a manually-managed span returned by allocManual.
-// stat must be the same as the stat passed to the allocManual that
+// typ must be the same as the spanAllocType passed to the allocManual that
 // allocated s.
 //
 // This must only be called when gcphase == _GCoff. See mSpanState for
@@ -1339,16 +1370,14 @@ func (h *mheap) freeSpan(s *mspan) {
 // the heap lock. See mheap for details.
 //
 //go:systemstack
-func (h *mheap) freeManual(s *mspan, stat *uint64) {
+func (h *mheap) freeManual(s *mspan, typ spanAllocType) {
 	s.needzero = 1
 	lock(&h.lock)
-	mSysStatDec(stat, s.npages*pageSize)
-	mSysStatInc(&memstats.heap_sys, s.npages*pageSize)
-	h.freeSpanLocked(s, false, true)
+	h.freeSpanLocked(s, typ)
 	unlock(&h.lock)
 }
 
-func (h *mheap) freeSpanLocked(s *mspan, acctinuse, acctidle bool) {
+func (h *mheap) freeSpanLocked(s *mspan, typ spanAllocType) {
 	switch s.state.get() {
 	case mSpanManual:
 		if s.allocCount != 0 {
@@ -1368,12 +1397,21 @@ func (h *mheap) freeSpanLocked(s *mspan, acctinuse, acctidle bool) {
 		throw("mheap.freeSpanLocked - invalid span state")
 	}
 
-	if acctinuse {
+	// Update stats.
+	//
+	// Mirrors the code in allocSpan.
+	switch typ {
+	case spanAllocHeap:
 		mSysStatDec(&memstats.heap_inuse, s.npages*pageSize)
+	case spanAllocStack:
+		mSysStatDec(&memstats.stacks_inuse, s.npages*pageSize)
+	case spanAllocPtrScalarBits, spanAllocWorkBuf:
+		mSysStatDec(&memstats.gc_sys, s.npages*pageSize)
 	}
-	if acctidle {
-		mSysStatInc(&memstats.heap_idle, s.npages*pageSize)
+	if typ.manual() {
+		mSysStatInc(&memstats.heap_sys, s.npages*pageSize)
 	}
+	mSysStatInc(&memstats.heap_idle, s.npages*pageSize)
 
 	// Mark the space as free.
 	h.pages.free(s.base(), s.npages)
diff --git a/src/runtime/stack.go b/src/runtime/stack.go
index 2afc2635aa..7b9dce5393 100644
--- a/src/runtime/stack.go
+++ b/src/runtime/stack.go
@@ -187,7 +187,7 @@ func stackpoolalloc(order uint8) gclinkptr {
 	lockWithRankMayAcquire(&mheap_.lock, lockRankMheap)
 	if s == nil {
 		// no free stacks. Allocate another span worth.
-		s = mheap_.allocManual(_StackCacheSize>>_PageShift, &memstats.stacks_inuse)
+		s = mheap_.allocManual(_StackCacheSize>>_PageShift, spanAllocStack)
 		if s == nil {
 			throw("out of memory")
 		}
@@ -251,7 +251,7 @@ func stackpoolfree(x gclinkptr, order uint8) {
 		stackpool[order].item.span.remove(s)
 		s.manualFreeList = 0
 		osStackFree(s)
-		mheap_.freeManual(s, &memstats.stacks_inuse)
+		mheap_.freeManual(s, spanAllocStack)
 	}
 }
 
@@ -396,7 +396,7 @@ func stackalloc(n uint32) stack {
 
 		if s == nil {
 			// Allocate a new stack from the heap.
-			s = mheap_.allocManual(npage, &memstats.stacks_inuse)
+			s = mheap_.allocManual(npage, spanAllocStack)
 			if s == nil {
 				throw("out of memory")
 			}
@@ -480,7 +480,7 @@ func stackfree(stk stack) {
 			// Free the stack immediately if we're
 			// sweeping.
 			osStackFree(s)
-			mheap_.freeManual(s, &memstats.stacks_inuse)
+			mheap_.freeManual(s, spanAllocStack)
 		} else {
 			// If the GC is running, we can't return a
 			// stack span to the heap because it could be
@@ -1193,7 +1193,7 @@ func freeStackSpans() {
 				list.remove(s)
 				s.manualFreeList = 0
 				osStackFree(s)
-				mheap_.freeManual(s, &memstats.stacks_inuse)
+				mheap_.freeManual(s, spanAllocStack)
 			}
 			s = next
 		}
@@ -1207,7 +1207,7 @@ func freeStackSpans() {
 			next := s.next
 			stackLarge.free[i].remove(s)
 			osStackFree(s)
-			mheap_.freeManual(s, &memstats.stacks_inuse)
+			mheap_.freeManual(s, spanAllocStack)
 			s = next
 		}
 	}