diff --git a/std/heap.zig b/std/heap.zig
index 84ed469763289edbaa1f2bfc9fbcc0d3d2a1353b..dd5cfa4cd7790248a2752e19c704fdae03a46840 100644
--- a/std/heap.zig
+++ b/std/heap.zig
@@ -143,8 +143,9 @@ pub const DirectAllocator = struct {
                 return result;
             },
             Os.windows => {
+                if (old_mem.len == 0) return alloc(allocator, new_size, new_align);
+
                 const self = @fieldParentPtr(DirectAllocator, "allocator", allocator);
-
                 const old_adjusted_addr = @ptrToInt(old_mem.ptr);
                 const old_record_addr = old_adjusted_addr + old_mem.len;
                 const root_addr = @intToPtr(*align(1) usize, old_record_addr).*;
diff --git a/std/os/windows/util.zig b/std/os/windows/util.zig
index 24039967a1965dbb1c6b99f2acc3226c2412cda7..72c84502e3695aa7fba7705e6983b9af18b137f7 100644
--- a/std/os/windows/util.zig
+++ b/std/os/windows/util.zig
@@ -197,7 +197,7 @@ pub fn createWindowsEnvBlock(allocator: *mem.Allocator, env_map: *const BufMap)
     i += 1;
     result[i] = 0;
     i += 1;
-    return allocator.shrink(u16, result, i);
+    return allocator.shrink(result, i);
 }
 
 pub fn windowsFindFirstFile(