diff --git a/src/pkg/encoding/json/encode.go b/src/pkg/encoding/json/encode.go
index 042142d2c53..eac14a47ed7 100644
--- a/src/pkg/encoding/json/encode.go
+++ b/src/pkg/encoding/json/encode.go
@@ -79,7 +79,8 @@ import (
 //    Int64String int64 `json:",string"`
 //
 // The key name will be used if it's a non-empty string consisting of
-// only Unicode letters, digits, dollar signs, hyphens, and underscores.
+// only Unicode letters, digits, dollar signs, percent signs, hyphens,
+// underscores and slashes.
 //
 // Map values encode as JSON objects.
 // The map's key type must be string; the object keys are used directly
diff --git a/src/pkg/encoding/json/tagkey_test.go b/src/pkg/encoding/json/tagkey_test.go
index 1a15241cb0c..bba5730353d 100644
--- a/src/pkg/encoding/json/tagkey_test.go
+++ b/src/pkg/encoding/json/tagkey_test.go
@@ -9,7 +9,7 @@ import (
 )
 
 type basicLatin2xTag struct {
-	V string `json:"$-"`
+	V string `json:"$%-/"`
 }
 
 type basicLatin3xTag struct {
@@ -53,7 +53,7 @@ type badFormatTag struct {
 }
 
 type badCodeTag struct {
-	Z string `json:" !\"#%&'()*+,./"`
+	Z string `json:" !\"#&'()*+,."`
 }
 
 var structTagObjectKeyTests = []struct {
@@ -61,7 +61,7 @@ var structTagObjectKeyTests = []struct {
 	value string
 	key   string
 }{
-	{basicLatin2xTag{"2x"}, "2x", "$-"},
+	{basicLatin2xTag{"2x"}, "2x", "$%-/"},
 	{basicLatin3xTag{"3x"}, "3x", "0123456789"},
 	{basicLatin4xTag{"4x"}, "4x", "ABCDEFGHIJKLMO"},
 	{basicLatin5xTag{"5x"}, "5x", "PQRSTUVWXYZ_"},