diff --git a/cmd/vet/structtag.go b/cmd/vet/structtag.go
index 5da39046..a2b7d305 100644
--- a/cmd/vet/structtag.go
+++ b/cmd/vet/structtag.go
@@ -7,9 +7,12 @@
 package main
 
 import (
+	"errors"
 	"go/ast"
 	"reflect"
 	"strconv"
+	"strings"
+	"unicode"
 )
 
 func init() {
@@ -32,13 +35,8 @@ func checkCanonicalFieldTag(f *File, node ast.Node) {
 		return
 	}
 
-	// Check tag for validity by appending
-	// new key:value to end and checking that
-	// the tag parsing code can find it.
-	st := reflect.StructTag(tag + ` _gofix:"_magic"`)
-	if st.Get("_gofix") != "_magic" {
-		f.Badf(field.Pos(), "struct field tag %s not compatible with reflect.StructTag.Get", field.Tag.Value)
-		return
+	if err := validateStructTag(tag); err != nil {
+		f.Badf(field.Pos(), "struct field tag %s not compatible with reflect.StructTag.Get: %s", field.Tag.Value, err)
 	}
 
 	// Check for use of json or xml tags with unexported fields.
@@ -53,6 +51,7 @@ func checkCanonicalFieldTag(f *File, node ast.Node) {
 		return
 	}
 
+	st := reflect.StructTag(tag)
 	for _, enc := range [...]string{"json", "xml"} {
 		if st.Get(enc) != "" {
 			f.Badf(field.Pos(), "struct field %s has %s tag but is not exported", field.Names[0].Name, enc)
@@ -60,3 +59,44 @@ func checkCanonicalFieldTag(f *File, node ast.Node) {
 		}
 	}
 }
+
+var (
+	errTagSyntax      = errors.New("bad syntax for struct tag pair")
+	errTagKeySyntax   = errors.New("bad syntax for struct tag key")
+	errTagValueSyntax = errors.New("bad syntax for struct tag value")
+)
+
+// validateStructTag parses the struct tag and returns an error if it is not
+// in the canonical format, which is a space-separated list of key:"value"
+// settings.
+func validateStructTag(tag string) error {
+	elems := strings.Split(tag, " ")
+	for _, elem := range elems {
+		if elem == "" {
+			continue
+		}
+		fields := strings.SplitN(elem, ":", 2)
+		if len(fields) != 2 {
+			return errTagSyntax
+		}
+		key, value := fields[0], fields[1]
+		if len(key) == 0 || len(value) < 2 {
+			return errTagSyntax
+		}
+		// Key must not contain control characters or quotes.
+		for _, r := range key {
+			if r == '"' || unicode.IsControl(r) {
+				return errTagKeySyntax
+			}
+		}
+		if value[0] != '"' || value[len(value)-1] != '"' {
+			return errTagValueSyntax
+		}
+		// Value must be quoted string
+		_, err := strconv.Unquote(value)
+		if err != nil {
+			return errTagValueSyntax
+		}
+	}
+	return nil
+}
diff --git a/cmd/vet/testdata/structtag.go b/cmd/vet/testdata/structtag.go
index 55462e5a..1e1ebf8f 100644
--- a/cmd/vet/testdata/structtag.go
+++ b/cmd/vet/testdata/structtag.go
@@ -2,14 +2,17 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// This file contains tests for the structtag checker.
-
 // This file contains the test for canonical struct tags.
 
 package testdata
 
 type StructTagTest struct {
-	X int "hello" // ERROR "not compatible with reflect.StructTag.Get"
+	A   int "hello"            // ERROR "not compatible with reflect.StructTag.Get: bad syntax for struct tag pair"
+	B   int "\tx:\"y\""        // ERROR "not compatible with reflect.StructTag.Get: bad syntax for struct tag key"
+	C   int "x:\"y\"\tx:\"y\"" // ERROR "not compatible with reflect.StructTag.Get"
+	D   int "x:`y`"            // ERROR "not compatible with reflect.StructTag.Get: bad syntax for struct tag value"
+	OK0 int `x:"y" u:"v" w:""`
+	OK1 int `x:"y:z" u:"v" w:""` // note multiple colons.
 }
 
 type UnexportedEncodingTagTest struct {