diff --git a/lib/std/private/threadtypes.nim b/lib/std/private/threadtypes.nim
index a1cdf21dc0f7..f68a939bb661 100644
--- a/lib/std/private/threadtypes.nim
+++ b/lib/std/private/threadtypes.nim
@@ -1,4 +1,5 @@
 include system/inclrtl
+import std/atomics
 
 const hasSharedHeap* = defined(boehmgc) or defined(gogc) # don't share heaps; every thread has its own
 
@@ -166,9 +167,9 @@ type
     core*: PGcThread
     sys*: SysThread
     when TArg is void:
-      dataFn*: proc () {.nimcall, gcsafe.}
+      dataFn*: Atomic[proc () {.nimcall, gcsafe.}]
     else:
-      dataFn*: proc (m: TArg) {.nimcall, gcsafe.}
+      dataFn*: Atomic[proc (m: TArg) {.nimcall, gcsafe.}]
       data*: TArg
     when hasAllocStack:
       rawStack*: pointer
diff --git a/lib/std/typedthreads.nim b/lib/std/typedthreads.nim
index 494baa8abf9f..51cf82374ffb 100644
--- a/lib/std/typedthreads.nim
+++ b/lib/std/typedthreads.nim
@@ -78,6 +78,7 @@ deinitLock(l)
 
 import std/private/[threadtypes]
 export Thread
+import std/atomics
 
 import system/ansi_c
 
@@ -149,9 +150,10 @@ else:
     nimThreadProcWrapperBody(closure)
 {.pop.}
 
-proc running*[TArg](t: Thread[TArg]): bool {.inline.} =
+proc running*[TArg](t: var Thread[TArg]): bool {.inline.} =
   ## Returns true if `t` is running.
-  result = t.dataFn != nil
+  let dataFn = t.dataFn.load()
+  result = dataFn != nil
 
 proc handle*[TArg](t: Thread[TArg]): SysThread {.inline.} =
   ## Returns the thread handle of `t`.
@@ -202,7 +204,7 @@ when false:
     else:
       discard pthread_cancel(t.sys)
     when declared(registerThread): unregisterThread(addr(t))
-    t.dataFn = nil
+    t.dataFn.store nil
     ## if thread `t` already exited, `t.core` will be `null`.
     if not isNil(t.core):
       deallocThreadStorage(t.core)
@@ -220,7 +222,7 @@ when hostOS == "windows":
     t.core = cast[PGcThread](allocThreadStorage(sizeof(GcThread)))
 
     when TArg isnot void: t.data = param
-    t.dataFn = tp
+    t.dataFn.store tp
     when hasSharedHeap: t.core.stackSize = ThreadStackSize
     var dummyThreadId: int32 = 0'i32
     t.sys = createThread(nil, ThreadStackSize, threadProcWrapper[TArg],
@@ -245,7 +247,7 @@ elif defined(genode):
     t.core = cast[PGcThread](allocThreadStorage(sizeof(GcThread)))
 
     when TArg isnot void: t.data = param
-    t.dataFn = tp
+    t.dataFn.store(tp)
     when hasSharedHeap: t.stackSize = ThreadStackSize
     t.sys.initThread(
       runtimeEnv,
@@ -269,7 +271,7 @@ else:
     t.core = cast[PGcThread](allocThreadStorage(sizeof(GcThread)))
 
     when TArg isnot void: t.data = param
-    t.dataFn = tp
+    t.dataFn.store(tp)
     when hasSharedHeap: t.core.stackSize = ThreadStackSize
     var a {.noinit.}: Pthread_attr
     doAssert pthread_attr_init(a) == 0
diff --git a/lib/system/threadimpl.nim b/lib/system/threadimpl.nim
index 093a920a1d53..95fb70f27b39 100644
--- a/lib/system/threadimpl.nim
+++ b/lib/system/threadimpl.nim
@@ -1,3 +1,5 @@
+import std/atomics
+
 var
   nimThreadDestructionHandlers* {.rtlThreadVar.}: seq[proc () {.closure, gcsafe, raises: [].}]
 when not defined(boehmgc) and not hasSharedHeap and not defined(gogc) and not defined(gcRegions):
@@ -50,10 +52,11 @@ when defined(boehmgc):
     boehmGC_register_my_thread(sb)
     try:
       let thrd = cast[ptr Thread[TArg]](thrd)
+      let dataFn = thrd.dataFn.load()
       when TArg is void:
-        thrd.dataFn()
+        dataFn()
       else:
-        thrd.dataFn(thrd.data)
+        dataFn(thrd.data)
     except:
       threadTrouble()
     finally:
@@ -62,15 +65,16 @@ when defined(boehmgc):
 else:
   proc threadProcWrapDispatch[TArg](thrd: ptr Thread[TArg]) {.raises: [].} =
     try:
+      let dataFn = thrd.dataFn.load()
       when TArg is void:
-        thrd.dataFn()
+        dataFn()
       else:
         when defined(nimV2):
-          thrd.dataFn(thrd.data)
+          dataFn(thrd.data)
         else:
           var x: TArg = default(TArg)
           deepCopy(x, thrd.data)
-          thrd.dataFn(x)
+          dataFn(x)
     except:
       threadTrouble()
     finally:
@@ -107,5 +111,5 @@ template nimThreadProcWrapperBody*(closure: untyped): untyped =
 
   # mark as not running anymore:
   thrd.core = nil
-  thrd.dataFn = nil
+  thrd.dataFn.store(nil)
   deallocThreadStorage(cast[pointer](core))