diff --git a/dlls/msvcp110/msvcp110.spec b/dlls/msvcp110/msvcp110.spec
index 5eec1a003e0..2de95bf94ef 100644
--- a/dlls/msvcp110/msvcp110.spec
+++ b/dlls/msvcp110/msvcp110.spec
@@ -3823,7 +3823,7 @@
 @ cdecl _Mtx_getconcrtcs(ptr)
 @ cdecl _Mtx_init(ptr long)
 @ cdecl _Mtx_lock(ptr)
-@ stub _Mtx_reset_owner
+@ cdecl _Mtx_reset_owner(ptr)
 @ stub _Mtx_timedlock
 @ cdecl _Mtx_trylock(ptr)
 @ cdecl _Mtx_unlock(ptr)
diff --git a/dlls/msvcp120/msvcp120.spec b/dlls/msvcp120/msvcp120.spec
index 18e13be46b8..e0adc83113f 100644
--- a/dlls/msvcp120/msvcp120.spec
+++ b/dlls/msvcp120/msvcp120.spec
@@ -3768,7 +3768,7 @@
 @ cdecl _Mtx_getconcrtcs(ptr)
 @ cdecl _Mtx_init(ptr long)
 @ cdecl _Mtx_lock(ptr)
-@ stub _Mtx_reset_owner
+@ cdecl _Mtx_reset_owner(ptr)
 @ stub _Mtx_timedlock
 @ cdecl _Mtx_trylock(ptr)
 @ cdecl _Mtx_unlock(ptr)
diff --git a/dlls/msvcp120_app/msvcp120_app.spec b/dlls/msvcp120_app/msvcp120_app.spec
index 72cdd258bd0..dd8e3ebf173 100644
--- a/dlls/msvcp120_app/msvcp120_app.spec
+++ b/dlls/msvcp120_app/msvcp120_app.spec
@@ -3768,7 +3768,7 @@
 @ cdecl _Mtx_getconcrtcs(ptr) msvcp120._Mtx_getconcrtcs
 @ cdecl _Mtx_init(ptr long) msvcp120._Mtx_init
 @ cdecl _Mtx_lock(ptr) msvcp120._Mtx_lock
-@ stub _Mtx_reset_owner
+@ cdecl _Mtx_reset_owner(ptr) msvcp120._Mtx_reset_owner
 @ stub _Mtx_timedlock
 @ cdecl _Mtx_trylock(ptr) msvcp120._Mtx_trylock
 @ cdecl _Mtx_unlock(ptr) msvcp120._Mtx_unlock
diff --git a/dlls/msvcp140/msvcp140.spec b/dlls/msvcp140/msvcp140.spec
index 05b5b0feac3..3de0318a4d5 100644
--- a/dlls/msvcp140/msvcp140.spec
+++ b/dlls/msvcp140/msvcp140.spec
@@ -3680,7 +3680,7 @@
 @ cdecl _Mtx_init(ptr long)
 @ cdecl _Mtx_init_in_situ(ptr long)
 @ cdecl _Mtx_lock(ptr)
-@ stub _Mtx_reset_owner
+@ cdecl _Mtx_reset_owner(ptr)
 @ stub _Mtx_timedlock
 @ cdecl _Mtx_trylock(ptr)
 @ cdecl _Mtx_unlock(ptr)
diff --git a/dlls/msvcp90/misc.c b/dlls/msvcp90/misc.c
index ef1f292f37e..18f05311a05 100644
--- a/dlls/msvcp90/misc.c
+++ b/dlls/msvcp90/misc.c
@@ -814,6 +814,13 @@ void __cdecl _Mtx_clear_owner(_Mtx_arg_t mtx)
     m->count--;
 }
 
+void __cdecl _Mtx_reset_owner(_Mtx_arg_t mtx)
+{
+    _Mtx_t m = MTX_T_FROM_ARG(mtx);
+    m->thread_id = GetCurrentThreadId();
+    m->count++;
+}
+
 static inline LONG interlocked_dec_if_nonzero( LONG *dest )
 {
     LONG val, tmp;
diff --git a/dlls/msvcp_win/msvcp_win.spec b/dlls/msvcp_win/msvcp_win.spec
index fb6fd5cd1c2..a15fb5c7ee3 100644
--- a/dlls/msvcp_win/msvcp_win.spec
+++ b/dlls/msvcp_win/msvcp_win.spec
@@ -3680,7 +3680,7 @@
 @ cdecl _Mtx_init(ptr long) msvcp140._Mtx_init
 @ cdecl _Mtx_init_in_situ(ptr long) msvcp140._Mtx_init_in_situ
 @ cdecl _Mtx_lock(ptr) msvcp140._Mtx_lock
-@ stub _Mtx_reset_owner
+@ cdecl _Mtx_reset_owner(ptr) msvcp140._Mtx_reset_owner
 @ stub _Mtx_timedlock
 @ cdecl _Mtx_trylock(ptr) msvcp140._Mtx_trylock
 @ cdecl _Mtx_unlock(ptr) msvcp140._Mtx_unlock