diff --git a/reactos/dll/ntdll/ldr/ldrinit.c b/reactos/dll/ntdll/ldr/ldrinit.c
index 8b6540242ac..5e222532ce6 100644
--- a/reactos/dll/ntdll/ldr/ldrinit.c
+++ b/reactos/dll/ntdll/ldr/ldrinit.c
@@ -508,7 +508,7 @@ LdrpInitializeThread(IN PCONTEXT Context)
 
     /* Allocate an Activation Context Stack */
     DPRINT("ActivationContextStack %p\n", NtCurrentTeb()->ActivationContextStackPointer);
-    Status = RtlAllocateActivationContextStack((PVOID*)&NtCurrentTeb()->ActivationContextStackPointer);
+    Status = RtlAllocateActivationContextStack(&NtCurrentTeb()->ActivationContextStackPointer);
     if (!NT_SUCCESS(Status))
     {
         DPRINT1("Warning: Unable to allocate ActivationContextStack\n");
@@ -1709,7 +1709,7 @@ LdrpInitializeProcess(IN PCONTEXT Context,
     }
 
     /* Allocate an Activation Context Stack */
-    Status = RtlAllocateActivationContextStack((PVOID *)&Teb->ActivationContextStackPointer);
+    Status = RtlAllocateActivationContextStack(&Teb->ActivationContextStackPointer);
     if (!NT_SUCCESS(Status)) return Status;
 
     // FIXME: Loader private heap is missing
diff --git a/reactos/include/asm/genincdata.c b/reactos/include/asm/genincdata.c
index 2f55a40efd9..bfd99090104 100644
--- a/reactos/include/asm/genincdata.c
+++ b/reactos/include/asm/genincdata.c
@@ -31,14 +31,14 @@ typedef struct _FIBER                                      /* Field offsets:  */
 {                                                          /* 32 bit   64 bit */
     /* this must be the first field */
     PVOID Parameter;                                       /*   0x00     0x00 */
-    struct _EXCEPTION_REGISTRATION_RECORD * ExceptionList; /*   0x04     0x08 */
+    PEXCEPTION_REGISTRATION_RECORD ExceptionList;          /*   0x04     0x08 */
     PVOID StackBase;                                       /*   0x08     0x10 */
     PVOID StackLimit;                                      /*   0x0C     0x18 */
     PVOID DeallocationStack;                               /*   0x10     0x20 */
     CONTEXT Context;                                       /*   0x14     0x28 */
     ULONG GuaranteedStackBytes;                            /*   0x2E0         */
     PVOID FlsData;                                         /*   0x2E4         */
-    PVOID ActivationContextStack;                          /*   0x2E8         */
+    PVOID /* PACTIVATION_CONTEXT_STACK */ ActivationContextStack; /*   0x2E8         */
 } FIBER, *PFIBER;
 
 typedef struct
diff --git a/reactos/include/ndk/rtlfuncs.h b/reactos/include/ndk/rtlfuncs.h
index cf2ee8541cc..ac709780f02 100644
--- a/reactos/include/ndk/rtlfuncs.h
+++ b/reactos/include/ndk/rtlfuncs.h
@@ -3503,7 +3503,7 @@ NTSYSAPI
 NTSTATUS
 NTAPI
 RtlAllocateActivationContextStack(
-    _In_ PVOID *Context
+    _In_ PACTIVATION_CONTEXT_STACK *Stack
 );
 
 NTSYSAPI
diff --git a/reactos/lib/rtl/actctx.c b/reactos/lib/rtl/actctx.c
index bdd371e63df..8c696f893c2 100644
--- a/reactos/lib/rtl/actctx.c
+++ b/reactos/lib/rtl/actctx.c
@@ -2429,7 +2429,7 @@ RtlDeactivateActivationContext( ULONG flags, ULONG_PTR cookie )
 
 VOID
 NTAPI
-RtlFreeActivationContextStack(PACTIVATION_CONTEXT_STACK Stack)
+RtlFreeActivationContextStack(IN PACTIVATION_CONTEXT_STACK Stack)
 {
     PRTL_ACTIVATION_CONTEXT_STACK_FRAME ActiveFrame, PrevFrame;
 
@@ -2775,15 +2775,15 @@ RtlFindActivationContextSectionString( ULONG flags, const GUID *guid, ULONG sect
 
 NTSTATUS
 NTAPI
-RtlAllocateActivationContextStack(IN PVOID *Context)
+RtlAllocateActivationContextStack(IN PACTIVATION_CONTEXT_STACK *Stack)
 {
     PACTIVATION_CONTEXT_STACK ContextStack;
 
     /* Check if it's already allocated */
-    if (*Context) return STATUS_SUCCESS;
+    if (*Stack) return STATUS_SUCCESS;
 
     /* Allocate space for the context stack */
-    ContextStack = RtlAllocateHeap(RtlGetProcessHeap(), HEAP_ZERO_MEMORY, sizeof (ACTIVATION_CONTEXT_STACK) );
+    ContextStack = RtlAllocateHeap(RtlGetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(ACTIVATION_CONTEXT_STACK));
     if (!ContextStack)
     {
         return STATUS_NO_MEMORY;
@@ -2796,7 +2796,7 @@ RtlAllocateActivationContextStack(IN PVOID *Context)
     ContextStack->NextCookieSequenceNumber = 1;
     ContextStack->StackId = 1; //TODO: Timer-based
 
-    *Context = ContextStack;
+    *Stack = ContextStack;
 
     return STATUS_SUCCESS;
 }