diff --git a/src/coreclr/vm/ceemain.cpp b/src/coreclr/vm/ceemain.cpp
index c2704acb8d4913..f3a8796aa12f36 100644
--- a/src/coreclr/vm/ceemain.cpp
+++ b/src/coreclr/vm/ceemain.cpp
@@ -1759,17 +1759,16 @@ static void __stdcall FiberDetachCallback(void* lpFlsData)
     }
 }
 
-bool InitFlsSlot()
+void InitFlsSlot()
 {
     // We use fiber detach callbacks to run our thread shutdown code because the fiber detach
     // callback is made without the OS loader lock
     g_flsIndex = FlsAlloc(FiberDetachCallback);
     if (g_flsIndex == FLS_OUT_OF_INDEXES)
     {
-        return false;
+        _ASSERTE(!"Initialization of an FLS slot failed.");
+        COMPlusThrowWin32();
     }
-
-    return true;
 }
 
 // Register the thread with OS to be notified when thread is about to be destroyed
diff --git a/src/coreclr/vm/ceemain.h b/src/coreclr/vm/ceemain.h
index fec164ea3920b7..69ba92d692d6d2 100644
--- a/src/coreclr/vm/ceemain.h
+++ b/src/coreclr/vm/ceemain.h
@@ -47,7 +47,7 @@ void ThreadDetaching();
 
 void EnsureTlsDestructionMonitor();
 #ifdef TARGET_WINDOWS
-bool InitFlsSlot();
+void InitFlsSlot();
 bool OsDetachThread(void* thread);
 #endif
 
diff --git a/src/coreclr/vm/threads.cpp b/src/coreclr/vm/threads.cpp
index 849a891f03bcda..7ffb9f4746d94a 100644
--- a/src/coreclr/vm/threads.cpp
+++ b/src/coreclr/vm/threads.cpp
@@ -1049,10 +1049,7 @@ void InitThreadManager()
     CONTRACTL_END;
 
 #ifdef TARGET_WINDOWS
-    if (!InitFlsSlot())
-    {
-        _ASSERTE_ALL_BUILDS(!"Initialization of a FLS slot failed.");
-    }
+    InitFlsSlot();
 #endif
 
     // All patched helpers should fit into one page.