diff --git a/reactos/include/psdk/windows.h b/reactos/include/psdk/windows.h
index 323964cd918..67b25150b2e 100644
--- a/reactos/include/psdk/windows.h
+++ b/reactos/include/psdk/windows.h
@@ -18,7 +18,7 @@
 #endif
 
 #if !defined(_X86_) && !defined(_AMD64_) && !defined(_IA64_) && !defined(_ALPHA_) && \
-    !defined(_ARM_) && !defined(_PPC_) && !defined(_MIPS_) && !defined(_68K_)
+    !defined(_ARM_) && !defined(_PPC_) && !defined(_MIPS_) && !defined(_68K_) && !defined(_SH_)
 
 #if defined(_M_AMD64) || defined(__x86_64__)
 #define _AMD64_
@@ -36,6 +36,8 @@
 #define _MIPS_
 #elif defined(_M_M68K) || defined(__68k__)
 #define _68K_
+#elif defined(_SHX_) || defined(__sh__)
+#define _SH_
 #endif
 
 #endif
diff --git a/reactos/include/psdk/winnt.h b/reactos/include/psdk/winnt.h
index 3e51663e8b9..80878405e60 100644
--- a/reactos/include/psdk/winnt.h
+++ b/reactos/include/psdk/winnt.h
@@ -2959,7 +2959,7 @@ typedef struct _LDT_ENTRY {
 #endif /* _LDT_ENTRY_DEFINED */
 
 /* FIXME: add more machines */
-#if defined(_X86_) && !defined(__PowerPC__)
+#if defined(_X86_)
 #define SIZE_OF_80387_REGISTERS    80
 #define CONTEXT_i386    0x10000
 #define CONTEXT_i486    0x10000
@@ -3015,7 +3015,7 @@ typedef struct _CONTEXT {
   DWORD SegSs;
   BYTE ExtendedRegisters[MAXIMUM_SUPPORTED_EXTENSION];
 } CONTEXT;
-#elif defined(__x86_64__)
+#elif defined(_AMD64_)
 
 #define CONTEXT_AMD64 0x100000
 
@@ -3464,7 +3464,7 @@ typedef struct _CONTEXT {
     DWORD ContextFlags;
     DWORD Fill[4];
 } CONTEXT;
-#elif defined(SHx)
+#elif defined(_SH_)
 
 /* These are the debug or break registers on the SH3 */
 typedef struct _DEBUG_REGISTERS {
diff --git a/reactos/include/xdk/winnt_old.h b/reactos/include/xdk/winnt_old.h
index 4488e4a795c..e5145092b65 100644
--- a/reactos/include/xdk/winnt_old.h
+++ b/reactos/include/xdk/winnt_old.h
@@ -1602,7 +1602,7 @@ typedef struct _LDT_ENTRY {
 #endif /* _LDT_ENTRY_DEFINED */
 
 /* FIXME: add more machines */
-#if defined(_X86_) && !defined(__PowerPC__)
+#if defined(_X86_)
 #define SIZE_OF_80387_REGISTERS    80
 #define CONTEXT_i386    0x10000
 #define CONTEXT_i486    0x10000
@@ -1658,7 +1658,7 @@ typedef struct _CONTEXT {
   DWORD SegSs;
   BYTE ExtendedRegisters[MAXIMUM_SUPPORTED_EXTENSION];
 } CONTEXT;
-#elif defined(__x86_64__)
+#elif defined(_AMD64_)
 
 #define CONTEXT_AMD64 0x100000
 
@@ -2107,7 +2107,7 @@ typedef struct _CONTEXT {
     DWORD ContextFlags;
     DWORD Fill[4];
 } CONTEXT;
-#elif defined(SHx)
+#elif defined(_SH_)
 
 /* These are the debug or break registers on the SH3 */
 typedef struct _DEBUG_REGISTERS {