diff --git a/misc/cgo/test/test.go b/misc/cgo/test/test.go
index b5009d43ce..8c69ad91ac 100644
--- a/misc/cgo/test/test.go
+++ b/misc/cgo/test/test.go
@@ -2200,3 +2200,7 @@ func test32579(t *testing.T) {
 // issue 38649
 
 var issue38649 C.netbsd_gid = 42
+
+// issue 39877
+
+var issue39877 *C.void = nil
diff --git a/src/cmd/cgo/out.go b/src/cmd/cgo/out.go
index 6b40a255d5..6c221473e0 100644
--- a/src/cmd/cgo/out.go
+++ b/src/cmd/cgo/out.go
@@ -98,6 +98,11 @@ func (p *Package) writeDefs() {
 
 	typedefNames := make([]string, 0, len(typedef))
 	for name := range typedef {
+		if name == "_Ctype_void" {
+			// We provide an appropriate declaration for
+			// _Ctype_void below (#39877).
+			continue
+		}
 		typedefNames = append(typedefNames, name)
 	}
 	sort.Strings(typedefNames)