diff --git a/core/sys/win32/crt.odin b/core/sys/win32/crt.odin
index d89f1cf96..983f2505b 100644
--- a/core/sys/win32/crt.odin
+++ b/core/sys/win32/crt.odin
@@ -1,3 +1,4 @@
+// +build windows
 package win32
 
 import "core:strings";
diff --git a/core/sys/windows/advapi32.odin b/core/sys/windows/advapi32.odin
index 31e542e37..7e14aa3f8 100644
--- a/core/sys/windows/advapi32.odin
+++ b/core/sys/windows/advapi32.odin
@@ -1,3 +1,4 @@
+// +build windows
 package sys_windows
 
 foreign import advapi32 "system:Advapi32.lib"
diff --git a/core/sys/windows/bcrypt.odin b/core/sys/windows/bcrypt.odin
index 5d6c6811f..bfb75d259 100644
--- a/core/sys/windows/bcrypt.odin
+++ b/core/sys/windows/bcrypt.odin
@@ -1,3 +1,4 @@
+// +build windows
 package sys_windows
 
 foreign import bcrypt "system:Bcrypt.lib"
diff --git a/core/sys/windows/kernel32.odin b/core/sys/windows/kernel32.odin
index 9e50e2741..868d4f771 100644
--- a/core/sys/windows/kernel32.odin
+++ b/core/sys/windows/kernel32.odin
@@ -1,3 +1,4 @@
+// +build windows
 package sys_windows
 
 foreign import kernel32 "system:Kernel32.lib"
diff --git a/core/sys/windows/netapi32.odin b/core/sys/windows/netapi32.odin
index d9b41657e..bc77b3ffd 100644
--- a/core/sys/windows/netapi32.odin
+++ b/core/sys/windows/netapi32.odin
@@ -1,3 +1,4 @@
+// +build windows
 package sys_windows
 
 foreign import netapi32 "system:Netapi32.lib"
diff --git a/core/sys/windows/ntdll.odin b/core/sys/windows/ntdll.odin
index 0f7472f33..7bbe44e59 100644
--- a/core/sys/windows/ntdll.odin
+++ b/core/sys/windows/ntdll.odin
@@ -1,3 +1,4 @@
+// +build windows
 package sys_windows
 
 foreign import ntdll_lib "system:ntdll.lib"
diff --git a/core/sys/windows/shell32.odin b/core/sys/windows/shell32.odin
index b0c7e2dd9..70d8943bd 100644
--- a/core/sys/windows/shell32.odin
+++ b/core/sys/windows/shell32.odin
@@ -1,3 +1,4 @@
+// +build windows
 package sys_windows
 
 foreign import shell32 "system:Shell32.lib"
diff --git a/core/sys/windows/synchronization.odin b/core/sys/windows/synchronization.odin
index 6f864de03..1769bb0c8 100644
--- a/core/sys/windows/synchronization.odin
+++ b/core/sys/windows/synchronization.odin
@@ -1,3 +1,4 @@
+// +build windows
 package sys_windows
 
 foreign import Synchronization "system:Synchronization.lib"
diff --git a/core/sys/windows/types.odin b/core/sys/windows/types.odin
index 61ed343fe..146c1a813 100644
--- a/core/sys/windows/types.odin
+++ b/core/sys/windows/types.odin
@@ -1,3 +1,4 @@
+// +build windows
 package sys_windows
 
 import "core:c"
diff --git a/core/sys/windows/userenv.odin b/core/sys/windows/userenv.odin
index b57ef5f2d..92bc09a7e 100644
--- a/core/sys/windows/userenv.odin
+++ b/core/sys/windows/userenv.odin
@@ -1,3 +1,4 @@
+// +build windows
 package sys_windows
 
 foreign import userenv "system:Userenv.lib"
diff --git a/core/sys/windows/util.odin b/core/sys/windows/util.odin
index 5248cfdbf..ea395359c 100644
--- a/core/sys/windows/util.odin
+++ b/core/sys/windows/util.odin
@@ -1,3 +1,4 @@
+// +build windows
 package sys_windows
 
 import "core:strings"
diff --git a/core/sys/windows/ws2_32.odin b/core/sys/windows/ws2_32.odin
index 0cd462623..6be55216e 100644
--- a/core/sys/windows/ws2_32.odin
+++ b/core/sys/windows/ws2_32.odin
@@ -1,3 +1,4 @@
+// +build windows
 package sys_windows
 
 foreign import ws2_32 "system:Ws2_32.lib"