diff --git a/misc/cgo/test/issue42495.go b/misc/cgo/test/issue42495.go
new file mode 100644
index 0000000..509a67d
--- /dev/null
+++ b/misc/cgo/test/issue42495.go
@@ -0,0 +1,15 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgotest
+
+// typedef struct { } T42495A;
+// typedef struct { int x[0]; } T42495B;
+import "C"
+
+//export Issue42495A
+func Issue42495A(C.T42495A) {}
+
+//export Issue42495B
+func Issue42495B(C.T42495B) {}
diff --git a/src/cmd/cgo/out.go b/src/cmd/cgo/out.go
index 81b28e2..bb96379 100644
--- a/src/cmd/cgo/out.go
+++ b/src/cmd/cgo/out.go
@@ -985,7 +985,15 @@
 		// The results part of the argument structure must be
 		// initialized to 0 so the write barriers generated by
 		// the assignments to these fields in Go are safe.
-		fmt.Fprintf(fgcc, "\t%s %v _cgo_a = {0};\n", ctype, p.packedAttribute())
+		//
+		// We use a local static variable to get the zeroed
+		// value of the argument type. This avoids including
+		// string.h for memset, and is also robust to C++
+		// types with constructors. Both GCC and LLVM optimize
+		// this into just zeroing _cgo_a.
+		fmt.Fprintf(fgcc, "\ttypedef %s %v _cgo_argtype;\n", ctype, p.packedAttribute())
+		fmt.Fprintf(fgcc, "\tstatic _cgo_argtype _cgo_zero;\n")
+		fmt.Fprintf(fgcc, "\t_cgo_argtype _cgo_a = _cgo_zero;\n")
 		if gccResult != "void" && (len(fntype.Results.List) > 1 || len(fntype.Results.List[0].Names) > 1) {
 			fmt.Fprintf(fgcc, "\t%s r;\n", gccResult)
 		}