diff --git a/std/event.zig b/std/event.zig
index 3fad81a78b..589ab4cb5f 100644
--- a/std/event.zig
+++ b/std/event.zig
@@ -142,6 +142,9 @@ pub const Loop = struct {
                 epoll_op: u32,
                 eventfd: i32,
             },
+            builtin.Os.windows => struct {
+                base: ResumeNode,
+            },
             else => @compileError("unsupported OS"),
         };
 
diff --git a/std/heap.zig b/std/heap.zig
index 6d3fd05cdb..caf972e605 100644
--- a/std/heap.zig
+++ b/std/heap.zig
@@ -96,12 +96,12 @@ pub const DirectAllocator = struct {
             },
             Os.windows => {
                 const amt = n + alignment + @sizeOf(usize);
-                const optional_heap_handle = @atomicLoad(?HeapHandle, ?self.heap_handle, builtin.AtomicOrder.SeqCst);
+                const optional_heap_handle = @atomicLoad(?HeapHandle, &self.heap_handle, builtin.AtomicOrder.SeqCst);
                 const heap_handle = optional_heap_handle orelse blk: {
                     const hh = os.windows.HeapCreate(os.windows.HEAP_NO_SERIALIZE, amt, 0) orelse return error.OutOfMemory;
                     const other_hh = @cmpxchgStrong(?HeapHandle, &self.heap_handle, null, hh, builtin.AtomicOrder.SeqCst, builtin.AtomicOrder.SeqCst) orelse break :blk hh;
                     _ = os.windows.HeapDestroy(hh);
-                    break :blk other_hh;
+                    break :blk other_hh.?; // can't be null because of the cmpxchg
                 };
                 const ptr = os.windows.HeapAlloc(heap_handle, 0, amt) orelse return error.OutOfMemory;
                 const root_addr = @ptrToInt(ptr);
diff --git a/std/os/index.zig b/std/os/index.zig
index 021a29e3d5..94fdd9dc84 100644
--- a/std/os/index.zig
+++ b/std/os/index.zig
@@ -2806,6 +2806,11 @@ pub fn cpuCount(fallback_allocator: *mem.Allocator) CpuCountError!usize {
                 }
             }
         },
+        builtin.Os.windows => {
+            var system_info: windows.SYSTEM_INFO = undefined;
+            windows.GetSystemInfo(&system_info);
+            return @intCast(usize, system_info.dwNumberOfProcessors);
+        },
         else => @compileError("unsupported OS"),
     }
 }
diff --git a/std/os/windows/index.zig b/std/os/windows/index.zig
index d631c6adbf..571ac97fac 100644
--- a/std/os/windows/index.zig
+++ b/std/os/windows/index.zig
@@ -107,6 +107,7 @@ pub extern "kernel32" stdcallcc fn GetFinalPathNameByHandleA(
 
 pub extern "kernel32" stdcallcc fn GetProcessHeap() ?HANDLE;
 
+pub extern "kernel32" stdcallcc fn GetSystemInfo(lpSystemInfo: *SYSTEM_INFO) void;
 pub extern "kernel32" stdcallcc fn GetSystemTimeAsFileTime(*FILETIME) void;
 
 pub extern "kernel32" stdcallcc fn HeapCreate(flOptions: DWORD, dwInitialSize: SIZE_T, dwMaximumSize: SIZE_T) ?HANDLE;
@@ -204,6 +205,7 @@ pub const SIZE_T = usize;
 pub const TCHAR = if (UNICODE) WCHAR else u8;
 pub const UINT = c_uint;
 pub const ULONG_PTR = usize;
+pub const DWORD_PTR = ULONG_PTR;
 pub const UNICODE = false;
 pub const WCHAR = u16;
 pub const WORD = u16;
@@ -413,3 +415,22 @@ pub const FILETIME = extern struct {
     dwLowDateTime: DWORD,
     dwHighDateTime: DWORD,
 };
+
+pub const SYSTEM_INFO = extern struct {
+    anon1: extern union {
+        dwOemId: DWORD,
+        anon2: extern struct {
+            wProcessorArchitecture: WORD,
+            wReserved: WORD,
+        },
+    },
+    dwPageSize: DWORD,
+    lpMinimumApplicationAddress: LPVOID,
+    lpMaximumApplicationAddress: LPVOID,
+    dwActiveProcessorMask: DWORD_PTR,
+    dwNumberOfProcessors: DWORD,
+    dwProcessorType: DWORD,
+    dwAllocationGranularity: DWORD,
+    wProcessorLevel: WORD,
+    wProcessorRevision: WORD,
+};