diff --git a/core/sys/darwin/xnu_system_call_wrappers.odin b/core/sys/darwin/xnu_system_call_wrappers.odin
index 1188091a9..97a527e9f 100644
--- a/core/sys/darwin/xnu_system_call_wrappers.odin
+++ b/core/sys/darwin/xnu_system_call_wrappers.odin
@@ -233,6 +233,11 @@ _Proc_Bsdinfo :: struct {
 
 /*--==========================================================================--*/
 
+/* Get window size */
+TIOCGWINSZ :: 0x40087468
+
+/*--==========================================================================--*/
+
 syscall_fsync :: #force_inline proc "contextless" (fildes: c.int) -> bool {
 	return !(cast(bool)intrinsics.syscall(unix_offset_syscall(.fsync), uintptr(fildes)))
 }
diff --git a/core/sys/freebsd/constants.odin b/core/sys/freebsd/constants.odin
new file mode 100644
index 000000000..3188b32d6
--- /dev/null
+++ b/core/sys/freebsd/constants.odin
@@ -0,0 +1,5 @@
+package sys_freebsd
+
+/* Get window size */
+TIOCGWINSZ :: 0x40087468
+
diff --git a/core/sys/linux/constants.odin b/core/sys/linux/constants.odin
index b3bbcafb3..3fba74b4c 100644
--- a/core/sys/linux/constants.odin
+++ b/core/sys/linux/constants.odin
@@ -373,3 +373,6 @@ PTRACE_SECCOMP_GET_FILTER     :: PTrace_Seccomp_Get_Filter_Type(.SECCOMP_GET_FIL
 PTRACE_SECCOMP_GET_METADATA   :: PTrace_Seccomp_Get_Metadata_Type(.SECCOMP_GET_METADATA)
 PTRACE_GET_SYSCALL_INFO       :: PTrace_Get_Syscall_Info_Type(.GET_SYSCALL_INFO)
 PTRACE_GET_RSEQ_CONFIGURATION :: PTrace_Get_RSeq_Configuration_Type(.GET_RSEQ_CONFIGURATION)
+
+/* Get window size */
+TIOCGWINSZ :: 0x5413