diff --git a/wsdlgo/encoder.go b/wsdlgo/encoder.go
index 5198c40..267118c 100644
--- a/wsdlgo/encoder.go
+++ b/wsdlgo/encoder.go
@@ -28,6 +28,8 @@ import (
 	"golang.org/x/net/html/charset"
 )
 
+const fileHeader = "// Code generated by wsdl2go. DO NOT EDIT."
+
 // An Encoder generates Go code from WSDL definitions.
 type Encoder interface {
 	// Encode generates Go code from d.
@@ -224,7 +226,7 @@ func (ge *goEncoder) encode(w io.Writer, d *wsdl.Definitions) error {
 		}
 	}
 
-	fmt.Fprintf(w, "package %s\n\nimport (\n", ge.packageName)
+	fmt.Fprintf(w, "%s\n\npackage %s\n\nimport (\n", fileHeader, ge.packageName)
 	for pkg := range ge.needsStdPkg {
 		fmt.Fprintf(w, "%q\n", pkg)
 	}
diff --git a/wsdlgo/testdata/arrayexample.golden b/wsdlgo/testdata/arrayexample.golden
index 9cb5033..be8e571 100644
--- a/wsdlgo/testdata/arrayexample.golden
+++ b/wsdlgo/testdata/arrayexample.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package stockquotesoapbinding
 
 import (
diff --git a/wsdlgo/testdata/data.golden b/wsdlgo/testdata/data.golden
index 8063e85..5cd49ca 100644
--- a/wsdlgo/testdata/data.golden
+++ b/wsdlgo/testdata/data.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package dataendpointhttpbinding
 
 import (
diff --git a/wsdlgo/testdata/data_withkeyword.golden b/wsdlgo/testdata/data_withkeyword.golden
index 8063e85..5cd49ca 100644
--- a/wsdlgo/testdata/data_withkeyword.golden
+++ b/wsdlgo/testdata/data_withkeyword.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package dataendpointhttpbinding
 
 import (
diff --git a/wsdlgo/testdata/localimport.golden b/wsdlgo/testdata/localimport.golden
index aeb4ddf..e36d887 100644
--- a/wsdlgo/testdata/localimport.golden
+++ b/wsdlgo/testdata/localimport.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package stockquotesoapbinding
 
 import (
diff --git a/wsdlgo/testdata/localimport_choice.golden b/wsdlgo/testdata/localimport_choice.golden
index f3f8551..4131fa5 100644
--- a/wsdlgo/testdata/localimport_choice.golden
+++ b/wsdlgo/testdata/localimport_choice.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package stockquotesoapbinding
 
 import (
diff --git a/wsdlgo/testdata/memcache.golden b/wsdlgo/testdata/memcache.golden
index 18eeff8..cbbaef9 100644
--- a/wsdlgo/testdata/memcache.golden
+++ b/wsdlgo/testdata/memcache.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package memoryservice
 
 import (
diff --git a/wsdlgo/testdata/soap12wcf.golden b/wsdlgo/testdata/soap12wcf.golden
index 1f73d21..ba205fd 100644
--- a/wsdlgo/testdata/soap12wcf.golden
+++ b/wsdlgo/testdata/soap12wcf.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package testsoap12binding
 
 import (
diff --git a/wsdlgo/testdata/tpexample1.golden b/wsdlgo/testdata/tpexample1.golden
index 9ee2ac1..56629b6 100644
--- a/wsdlgo/testdata/tpexample1.golden
+++ b/wsdlgo/testdata/tpexample1.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package hello_binding
 
 import (
diff --git a/wsdlgo/testdata/w3cexample1.golden b/wsdlgo/testdata/w3cexample1.golden
index 84dd6b0..a1b7f2a 100644
--- a/wsdlgo/testdata/w3cexample1.golden
+++ b/wsdlgo/testdata/w3cexample1.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package internal
 
 import (
diff --git a/wsdlgo/testdata/w3cexample2.golden b/wsdlgo/testdata/w3cexample2.golden
index 6f8a843..0a3cb25 100644
--- a/wsdlgo/testdata/w3cexample2.golden
+++ b/wsdlgo/testdata/w3cexample2.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package internal
 
 import (
diff --git a/wsdlgo/testdata/w3example1.golden b/wsdlgo/testdata/w3example1.golden
index 3511508..5836a43 100644
--- a/wsdlgo/testdata/w3example1.golden
+++ b/wsdlgo/testdata/w3example1.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package endorsementsearchsoapbinding
 
 import (
diff --git a/wsdlgo/testdata/w3example2.golden b/wsdlgo/testdata/w3example2.golden
index 09509a0..b4fa266 100644
--- a/wsdlgo/testdata/w3example2.golden
+++ b/wsdlgo/testdata/w3example2.golden
@@ -1,3 +1,5 @@
+// Code generated by wsdl2go. DO NOT EDIT.
+
 package stockquotesoapbinding
 
 import (