3 files changed, 15 insertions, 3 deletions
diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go
index 41875d2264..e52f9e6bd5 100644
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -985,7 +985,7 @@ func stdcall(fn stdFunction) uintptr {
 func stdcall0(fn stdFunction) uintptr {
 	mp := getg().m
 	mp.libcall.n = 0
-	mp.libcall.args = uintptr(noescape(unsafe.Pointer(&fn))) // it's unused but must be non-nil, otherwise crashes
+	mp.libcall.args = 0
 	return stdcall(fn)
 }
 
diff --git a/src/runtime/sys_windows_386.s b/src/runtime/sys_windows_386.s
index cb854c52e0..2efde4515b 100644
--- a/src/runtime/sys_windows_386.s
+++ b/src/runtime/sys_windows_386.s
@@ -14,13 +14,18 @@
 // void runtime·asmstdcall(void *c);
 TEXT runtime·asmstdcall(SB),NOSPLIT,$0
 	MOVL	fn+0(FP), BX
+	MOVL	SP, BP	// save stack pointer
 
 	// SetLastError(0).
 	MOVL	$0, 0x34(FS)
 
+	MOVL	libcall_n(BX), CX
+
+	// Fast version, do not store args on the stack.
+	CMPL	CX, $0
+	JE	docall
+
 	// Copy args to the stack.
-	MOVL	SP, BP
-	MOVL	libcall_n(BX), CX	// words
 	MOVL	CX, AX
 	SALL	$2, AX
 	SUBL	AX, SP			// room for args
@@ -29,6 +34,7 @@ TEXT runtime·asmstdcall(SB),NOSPLIT,$0
 	CLD
 	REP; MOVSL
 
+docall:
 	// Call stdcall or cdecl function.
 	// DI SI BP BX are preserved, SP is not
 	CALL	libcall_fn(BX)
diff --git a/src/runtime/sys_windows_amd64.s b/src/runtime/sys_windows_amd64.s
index 6d26bd3447..4a14b45c63 100644
--- a/src/runtime/sys_windows_amd64.s
+++ b/src/runtime/sys_windows_amd64.s
@@ -29,6 +29,11 @@ TEXT runtime·asmstdcall(SB),NOSPLIT,$16
 
 	SUBQ	$(const_maxArgs*8), SP	// room for args
 
+	// Fast version, do not store args on the stack nor
+	// load them into registers.
+	CMPL	CX, $0
+	JE	docall
+
 	// Fast version, do not store args on the stack.
 	CMPL	CX, $4
 	JLE	loadregs
@@ -59,6 +64,7 @@ loadregs:
 	MOVQ	R8, X2
 	MOVQ	R9, X3
 
+docall:
 	// Call stdcall function.
 	CALL	AX