diff --git a/protoc-gen-go/retag/retag.go b/protoc-gen-go/retag/retag.go
index 31b3b0ac92..14aa321ed4 100644
--- a/protoc-gen-go/retag/retag.go
+++ b/protoc-gen-go/retag/retag.go
@@ -5,6 +5,7 @@ import (
 	"bytes"
 	"fmt"
 	"os"
+	"regexp"
 	"strconv"
 	"strings"
 
@@ -52,6 +53,7 @@ func (r *retag) getStructTags(filename string) {
 
 	r.tags = make(map[string]string)
 	var begin bool
+	var oneof bool
 	var comment bool
 	var msgName string
 	reader := bufio.NewReader(file)
@@ -61,6 +63,10 @@ func (r *retag) getStructTags(filename string) {
 			break
 		}
 
+		if len(strings.TrimSpace(string(line))) == 0 {
+			continue
+		}
+
 		if strings.HasPrefix(strings.TrimSpace(string(line)), "/*") {
 			comment = true
 		}
@@ -74,12 +80,22 @@ func (r *retag) getStructTags(filename string) {
 			continue
 		}
 
+		if strings.HasPrefix(strings.TrimSpace(string(line)), "oneof") {
+			oneof = true
+			continue
+		}
+
 		if strings.HasPrefix(strings.TrimSpace(string(line)), "message") {
 			begin = true
 			msgName = strings.Fields(string(line))[1]
 			continue
 		}
 
+		if oneof == true && strings.TrimSpace(string(line))[0] == '}' {
+			oneof = false
+			continue
+		}
+
 		if begin == true && line[0] == '}' {
 			begin = false
 			continue
@@ -107,28 +123,21 @@ func (r *retag) getStructTags(filename string) {
 	}
 }
 
+var reFnT *regexp.Regexp = regexp.MustCompile(`^\s*(?:repeated)?\s*(map<[^>]+>|[^\s]+)\s*([^\s]+)\s*=\s*\d+\s*;\s*(//.*(json:"[^"]+").*)?`)
+
 func getFieldTag(line string, msgName string) (field string, tag string) {
-	fts := strings.Split(line, "//")
-	tag = fts[1]
-	fs := strings.Fields(fts[0])
-	fsl := len(fs)
-	field = msgName + "."
-	for i := 0; i < fsl; i++ {
-		if i == fsl-1 {
-			field += fs[i]
-			break
-		} else {
-			if fs[i+1] == "=" {
-				field += fs[i]
-				break
-			}
-		}
+	m := reFnT.FindAllStringSubmatch(line, 4)
+	if len(m) < 1 {
+		fmt.Fprintf(os.Stderr, "******\n\n\n%s\n\n\n****\n", line)
 	}
-
-	tag = strings.TrimSpace(tag)
-	tag = strings.Trim(tag, "`")
-	tag = trimInside(tag)
-
+	field = msgName + "." + m[0][2]
+	if m[0][4] != "" {
+		tag = m[0][4]
+	} else {
+		// fmt.Fprintf(os.Stderr, "no match %v %v\n", m, line)
+		tag = fmt.Sprintf(`json:"%s"`, m[0][2])
+	}
+	// fmt.Fprintf(os.Stderr, "2. field %v  tag %v\n", field, tag)
 	return
 }