diff --git a/src/windows.rs b/src/windows.rs
index 43930153c..6b2cd6e90 100644
--- a/src/windows.rs
+++ b/src/windows.rs
@@ -346,15 +346,6 @@ ffi! {
     pub const INVALID_HANDLE_VALUE: HANDLE = -1isize as HANDLE;
     pub const MAX_MODULE_NAME32: usize = 255;
     pub const MAX_PATH: usize = 260;
-    pub const CONTEXT_i386: u32 = 0x10000;
-    pub const CONTEXT_CONTROL: u32 = CONTEXT_i386 | 0x01; // SS:SP, CS:IP, FLAGS, B;
-    pub const CONTEXT_INTEGER: u32 = CONTEXT_i386 | 0x02; // AX, BX, CX, DX, SI, D;
-    pub const CONTEXT_SEGMENTS: u32 = CONTEXT_i386 | 0x04; // DS, ES, FS, G;
-    pub const CONTEXT_FLOATING_POINT: u32 = CONTEXT_i386 | 0x08; // 387 stat;
-    pub const CONTEXT_DEBUG_REGISTERS: u32 = CONTEXT_i386 | 0x10; // DB 0-3,6,;
-    pub const CONTEXT_EXTENDED_REGISTERS: u32 = CONTEXT_i386 | 0x20; // cpu specific extension;
-    pub const CONTEXT_ALL: u32 = CONTEXT_CONTROL | CONTEXT_INTEGER | CONTEXT_SEGMENTS |  CONTEXT_FLOATING_POINT | CONTEXT_DEBUG_REGISTERS |  CONTEXT_EXTENDED_REGISTERS;
-
 
     pub type DWORD = u32;
     pub type PDWORD = *mut u32;
@@ -575,6 +566,18 @@ ffi! {
         pub RegisterArea: [u8; 80],
         pub Spare0: DWORD,
     }
+
+    pub const CONTEXT_i386: DWORD = 0x00010000;
+    pub const CONTEXT_i486: DWORD = 0x00010000;
+    pub const CONTEXT_CONTROL: DWORD = CONTEXT_i386 | 0x00000001;
+    pub const CONTEXT_INTEGER: DWORD = CONTEXT_i386 | 0x00000002;
+    pub const CONTEXT_SEGMENTS: DWORD = CONTEXT_i386 | 0x00000004;
+    pub const CONTEXT_FLOATING_POINT: DWORD = CONTEXT_i386 | 0x00000008;
+    pub const CONTEXT_DEBUG_REGISTERS: DWORD = CONTEXT_i386 | 0x00000010;
+    pub const CONTEXT_EXTENDED_REGISTERS: DWORD = CONTEXT_i386 | 0x00000020;
+    pub const CONTEXT_FULL: DWORD = CONTEXT_CONTROL | CONTEXT_INTEGER | CONTEXT_SEGMENTS;
+    pub const CONTEXT_ALL: DWORD = CONTEXT_CONTROL | CONTEXT_INTEGER | CONTEXT_SEGMENTS
+        | CONTEXT_FLOATING_POINT | CONTEXT_DEBUG_REGISTERS | CONTEXT_EXTENDED_REGISTERS;
 }
 
 #[cfg(target_arch = "x86_64")]
@@ -642,6 +645,16 @@ ffi! {
         pub Low: u64,
         pub High: i64,
     }
+
+    pub const CONTEXT_AMD64: DWORD = 0x00100000;
+    pub const CONTEXT_CONTROL: DWORD = CONTEXT_AMD64 | 0x00000001;
+    pub const CONTEXT_INTEGER: DWORD = CONTEXT_AMD64 | 0x00000002;
+    pub const CONTEXT_SEGMENTS: DWORD = CONTEXT_AMD64 | 0x00000004;
+    pub const CONTEXT_FLOATING_POINT: DWORD = CONTEXT_AMD64 | 0x00000008;
+    pub const CONTEXT_DEBUG_REGISTERS: DWORD = CONTEXT_AMD64 | 0x00000010;
+    pub const CONTEXT_FULL: DWORD = CONTEXT_CONTROL | CONTEXT_INTEGER | CONTEXT_FLOATING_POINT;
+    pub const CONTEXT_ALL: DWORD = CONTEXT_CONTROL | CONTEXT_INTEGER | CONTEXT_SEGMENTS
+        | CONTEXT_FLOATING_POINT | CONTEXT_DEBUG_REGISTERS;
 }
 
 #[repr(C)]