diff --git a/auth/jwt/middleware.go b/auth/jwt/middleware.go
index e7dcb9d6a..c07d6e97e 100644
--- a/auth/jwt/middleware.go
+++ b/auth/jwt/middleware.go
@@ -66,11 +66,27 @@ func NewSigner(kid string, key []byte, method jwt.SigningMethod, claims jwt.Clai
 	}
 }
 
+// ClaimsFactory is a factory for jwt.Claims.
+// Useful in NewParser middleware.
+type ClaimsFactory func() jwt.Claims
+
+// MapClaimsFactory is a ClaimsFactory that returns 
+// an empty jwt.MapClaims.
+func MapClaimsFactory() jwt.Claims {
+    return jwt.MapClaims{}
+}
+
+// StandardClaimsFactory is a ClaimsFactory that returns 
+// an empty jwt.StandardClaims.
+func StandardClaimsFactory() jwt.Claims {
+    return &jwt.StandardClaims{}
+}
+
 // NewParser creates a new JWT token parsing middleware, specifying a
 // jwt.Keyfunc interface, the signing method and the claims type to be used. NewParser
 // adds the resulting  claims to endpoint context or returns error on invalid token.
 // Particularly useful for servers.
-func NewParser(keyFunc jwt.Keyfunc, method jwt.SigningMethod, claims jwt.Claims) endpoint.Middleware {
+func NewParser(keyFunc jwt.Keyfunc, method jwt.SigningMethod, newClaims ClaimsFactory) endpoint.Middleware {
 	return func(next endpoint.Endpoint) endpoint.Endpoint {
 		return func(ctx context.Context, request interface{}) (response interface{}, err error) {
 			// tokenString is stored in the context from the transport handlers.
@@ -85,7 +101,7 @@ func NewParser(keyFunc jwt.Keyfunc, method jwt.SigningMethod, claims jwt.Claims)
 			// of the token to identify which key to use, but the parsed token
 			// (head and claims) is provided to the callback, providing
 			// flexibility.
-			token, err := jwt.ParseWithClaims(tokenString, claims, func(token *jwt.Token) (interface{}, error) {
+			token, err := jwt.ParseWithClaims(tokenString, newClaims(), func(token *jwt.Token) (interface{}, error) {
 				// Don't forget to validate the alg is what you expect:
 				if token.Method != method {
 					return nil, ErrUnexpectedSigningMethod
diff --git a/auth/jwt/middleware_test.go b/auth/jwt/middleware_test.go
index 8a4520154..3278e13a7 100644
--- a/auth/jwt/middleware_test.go
+++ b/auth/jwt/middleware_test.go
@@ -2,6 +2,7 @@ package jwt
 
 import (
 	"context"
+	"sync"
 	"testing"
 	"time"
 
@@ -73,7 +74,7 @@ func TestJWTParser(t *testing.T) {
 		return key, nil
 	}
 
-	parser := NewParser(keys, method, jwt.MapClaims{})(e)
+	parser := NewParser(keys, method, MapClaimsFactory)(e)
 
 	// No Token is passed into the parser
 	_, err := parser(context.Background(), struct{}{})
@@ -93,7 +94,7 @@ func TestJWTParser(t *testing.T) {
 	}
 
 	// Invalid Method is used in the parser
-	badParser := NewParser(keys, invalidMethod, jwt.MapClaims{})(e)
+	badParser := NewParser(keys, invalidMethod, MapClaimsFactory)(e)
 	ctx = context.WithValue(context.Background(), JWTTokenContextKey, signedKey)
 	_, err = badParser(ctx, struct{}{})
 	if err == nil {
@@ -109,7 +110,7 @@ func TestJWTParser(t *testing.T) {
 		return []byte("bad"), nil
 	}
 
-	badParser = NewParser(invalidKeys, method, jwt.MapClaims{})(e)
+	badParser = NewParser(invalidKeys, method, MapClaimsFactory)(e)
 	ctx = context.WithValue(context.Background(), JWTTokenContextKey, signedKey)
 	_, err = badParser(ctx, struct{}{})
 	if err == nil {
@@ -133,7 +134,7 @@ func TestJWTParser(t *testing.T) {
 	}
 
 	// Test for malformed token error response
-	parser = NewParser(keys, method, &jwt.StandardClaims{})(e)
+	parser = NewParser(keys, method, StandardClaimsFactory)(e)
 	ctx = context.WithValue(context.Background(), JWTTokenContextKey, malformedKey)
 	ctx1, err = parser(ctx, struct{}{})
 	if want, have := ErrTokenMalformed, err; want != have {
@@ -141,7 +142,7 @@ func TestJWTParser(t *testing.T) {
 	}
 
 	// Test for expired token error response
-	parser = NewParser(keys, method, &jwt.StandardClaims{})(e)
+	parser = NewParser(keys, method, StandardClaimsFactory)(e)
 	expired := jwt.NewWithClaims(method, jwt.StandardClaims{ExpiresAt: time.Now().Unix() - 100})
 	token, err := expired.SignedString(key)
 	if err != nil {
@@ -154,7 +155,7 @@ func TestJWTParser(t *testing.T) {
 	}
 
 	// Test for not activated token error response
-	parser = NewParser(keys, method, &jwt.StandardClaims{})(e)
+	parser = NewParser(keys, method, StandardClaimsFactory)(e)
 	notactive := jwt.NewWithClaims(method, jwt.StandardClaims{NotBefore: time.Now().Unix() + 100})
 	token, err = notactive.SignedString(key)
 	if err != nil {
@@ -167,7 +168,7 @@ func TestJWTParser(t *testing.T) {
 	}
 
 	// test valid standard claims token
-	parser = NewParser(keys, method, &jwt.StandardClaims{})(e)
+	parser = NewParser(keys, method, StandardClaimsFactory)(e)
 	ctx = context.WithValue(context.Background(), JWTTokenContextKey, standardSignedKey)
 	ctx1, err = parser(ctx, struct{}{})
 	if err != nil {
@@ -182,7 +183,7 @@ func TestJWTParser(t *testing.T) {
 	}
 
 	// test valid customized claims token
-	parser = NewParser(keys, method, &customClaims{})(e)
+	parser = NewParser(keys, method, func() jwt.Claims { return &customClaims{} })(e)
 	ctx = context.WithValue(context.Background(), JWTTokenContextKey, customSignedKey)
 	ctx1, err = parser(ctx, struct{}{})
 	if err != nil {
@@ -199,3 +200,22 @@ func TestJWTParser(t *testing.T) {
 		t.Fatalf("JWT customClaims.MyProperty did not match: expecting %s got %s", myProperty, custCl.MyProperty)
 	}
 }
+
+func TestIssue562(t *testing.T) {
+	var (
+		kf  = func(token *jwt.Token) (interface{}, error) { return []byte("secret"), nil }
+		e   = NewParser(kf, jwt.SigningMethodHS256, MapClaimsFactory)(endpoint.Nop)
+		key = JWTTokenContextKey
+		val = "eyJhbGciOiJIUzI1NiIsImtpZCI6ImtpZCIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjoiZ28ta2l0In0.14M2VmYyApdSlV_LZ88ajjwuaLeIFplB8JpyNy0A19E"
+		ctx = context.WithValue(context.Background(), key, val)
+	)
+	wg := sync.WaitGroup{}
+	for i := 0; i < 100; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			e(ctx, struct{}{}) // fatal error: concurrent map read and map write
+		}()
+	}
+	wg.Wait()
+}