diff --git a/src/runtime/mheap.go b/src/runtime/mheap.go
index 1bf7bbecc0a5f..055dfeed99fc1 100644
--- a/src/runtime/mheap.go
+++ b/src/runtime/mheap.go
@@ -1190,6 +1190,16 @@ HaveSpan:
 		// heap_released since we already did so earlier.
 		sysUsed(unsafe.Pointer(s.base()), s.npages<<_PageShift)
 		s.scavenged = false
+
+		// Since we allocated out of a scavenged span, we just
+		// grew the RSS. Mitigate this by scavenging enough free
+		// space to make up for it.
+		//
+		// Also, scavengeLargest may cause coalescing, so prevent
+		// coalescing with s by temporarily changing its state.
+		s.state = mSpanManual
+		h.scavengeLargest(s.npages * pageSize)
+		s.state = mSpanFree
 	}
 	s.unusedsince = 0