diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go
index 1bf3309dfd..a2a124cd9d 100644
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -379,7 +379,6 @@ const (
 // in sys_windows_386.s and sys_windows_amd64.s:
 func externalthreadhandler()
 func getlasterror() uint32
-func setlasterror(err uint32)
 
 // When loading DLLs, we prefer to use LoadLibraryEx with
 // LOAD_LIBRARY_SEARCH_* flags, if available. LoadLibraryEx is not
diff --git a/src/runtime/sys_windows_386.s b/src/runtime/sys_windows_386.s
index b3972ac78d..c556e3a3c2 100644
--- a/src/runtime/sys_windows_386.s
+++ b/src/runtime/sys_windows_386.s
@@ -66,11 +66,6 @@ TEXT runtime·getlasterror(SB),NOSPLIT,$0
 	MOVL	AX, ret+0(FP)
 	RET
 
-TEXT runtime·setlasterror(SB),NOSPLIT,$0
-	MOVL	err+0(FP), AX
-	MOVL	AX, 0x34(FS)
-	RET
-
 // Called by Windows as a Vectored Exception Handler (VEH).
 // First argument is pointer to struct containing
 // exception record and context pointers.
diff --git a/src/runtime/sys_windows_amd64.s b/src/runtime/sys_windows_amd64.s
index 2bd7b74848..9cd14016b0 100644
--- a/src/runtime/sys_windows_amd64.s
+++ b/src/runtime/sys_windows_amd64.s
@@ -103,12 +103,6 @@ TEXT runtime·getlasterror(SB),NOSPLIT,$0
 	MOVL	AX, ret+0(FP)
 	RET
 
-TEXT runtime·setlasterror(SB),NOSPLIT,$0
-	MOVL	err+0(FP), AX
-	MOVQ	0x30(GS),	CX
-	MOVL	AX, 0x68(CX)
-	RET
-
 // Called by Windows as a Vectored Exception Handler (VEH).
 // First argument is pointer to struct containing
 // exception record and context pointers.
diff --git a/src/runtime/sys_windows_arm.s b/src/runtime/sys_windows_arm.s
index 1d928a4f7d..d2bdc50e3b 100644
--- a/src/runtime/sys_windows_arm.s
+++ b/src/runtime/sys_windows_arm.s
@@ -103,11 +103,6 @@ TEXT runtime·getlasterror(SB),NOSPLIT,$0
 	MOVW	R0, ret+0(FP)
 	RET
 
-TEXT runtime·setlasterror(SB),NOSPLIT|NOFRAME,$0
-	MRC	15, 0, R1, C13, C0, 2
-	MOVW	R0, 0x34(R1)
-	RET
-
 // Called by Windows as a Vectored Exception Handler (VEH).
 // First argument is pointer to struct containing
 // exception record and context pointers.