diff --git a/src/go/types/decl.go b/src/go/types/decl.go
index df01e925306034..571e172351befb 100644
--- a/src/go/types/decl.go
+++ b/src/go/types/decl.go
@@ -751,8 +751,12 @@ func (check *Checker) funcDecl(obj *Func, decl *declInfo) {
 	obj.typ = sig // guard against cycles
 	fdecl := decl.fdecl
 	check.funcType(sig, fdecl.Recv, fdecl.Type)
-	if sig.recv == nil && obj.name == "init" && (sig.params.Len() > 0 || sig.results.Len() > 0) {
-		check.errorf(fdecl, _InvalidInitSig, "func init must have no arguments and no return values")
+	if sig.recv == nil {
+		if obj.name == "init" && (sig.params.Len() > 0 || sig.results.Len() > 0) {
+			check.errorf(fdecl, _InvalidInitDecl, "func init must have no arguments and no return values")
+		} else if obj.name == "main" && check.pkg.name == "main" && (sig.params.Len() > 0 || sig.results.Len() > 0) {
+			check.errorf(fdecl, _InvalidMainDecl, "func main must have no arguments and no return values")
+		}
 		// ok to continue
 	}
 
diff --git a/src/go/types/errorcodes.go b/src/go/types/errorcodes.go
index c01a12c346d3e5..d27abdf4d48bf1 100644
--- a/src/go/types/errorcodes.go
+++ b/src/go/types/errorcodes.go
@@ -386,8 +386,8 @@ const (
 	// _InvalidInitSig occurs when an init function declares parameters or
 	// results.
 	//
-	// Example:
-	//  func init() int { return 1 }
+	// Deprecated: no longer emitted by the type checker. _InvalidInitDecl is
+	// used instead.
 	_InvalidInitSig
 
 	// _InvalidInitDecl occurs when init is declared as anything other than a
@@ -395,6 +395,9 @@ const (
 	//
 	// Example:
 	//  var init = 1
+	//
+	// Example:
+	//  func init() int { return 1 }
 	_InvalidInitDecl
 
 	// _InvalidMainDecl occurs when main is declared as anything other than a
diff --git a/src/go/types/testdata/main.src b/src/go/types/testdata/main.src
new file mode 100644
index 00000000000000..f892938d4acfa8
--- /dev/null
+++ b/src/go/types/testdata/main.src
@@ -0,0 +1,9 @@
+// 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 main
+
+func main()
+func /* ERROR "no arguments and no return values" */ main /* ERROR redeclared */ (int)
+func /* ERROR "no arguments and no return values" */ main /* ERROR redeclared */ () int