diff --git a/lib/pure/nimprof.nim b/lib/pure/nimprof.nim
index 3d0cc2154..132ea9462 100644
--- a/lib/pure/nimprof.nim
+++ b/lib/pure/nimprof.nim
@@ -60,6 +60,7 @@ when not defined(memProfiler):
     else: interval = intervalInUs * 1000 - tickCountCorrection
   
 when withThreads:
+  import locks
   var
     profilingLock: TLock