diff --git a/auth/jwt/transport.go b/auth/jwt/transport.go
index 6d02f7d..7be7db4 100644
--- a/auth/jwt/transport.go
+++ b/auth/jwt/transport.go
@@ -44,10 +44,10 @@
 
 // ToGRPCContext moves JWT token from grpc metadata to context. Particularly
 // userful for servers.
-func ToGRPCContext() grpc.RequestFunc {
-	return func(ctx context.Context, md *metadata.MD) context.Context {
+func ToGRPCContext() grpc.ServerRequestFunc {
+	return func(ctx context.Context, md metadata.MD) context.Context {
 		// capital "Key" is illegal in HTTP/2.
-		authHeader, ok := (*md)["authorization"]
+		authHeader, ok := md["authorization"]
 		if !ok {
 			return ctx
 		}
@@ -63,7 +63,7 @@
 
 // FromGRPCContext moves JWT token from context to grpc metadata. Particularly
 // useful for clients.
-func FromGRPCContext() grpc.RequestFunc {
+func FromGRPCContext() grpc.ClientRequestFunc {
 	return func(ctx context.Context, md *metadata.MD) context.Context {
 		token, ok := ctx.Value(JWTTokenContextKey).(string)
 		if ok {
diff --git a/auth/jwt/transport_test.go b/auth/jwt/transport_test.go
index 8b8922a..b04d76f 100644
--- a/auth/jwt/transport_test.go
+++ b/auth/jwt/transport_test.go
@@ -69,7 +69,7 @@
 	reqFunc := ToGRPCContext()
 
 	// No Authorization header is passed
-	ctx := reqFunc(context.Background(), &md)
+	ctx := reqFunc(context.Background(), md)
 	token := ctx.Value(JWTTokenContextKey)
 	if token != nil {
 		t.Error("Context should not contain a JWT Token")
@@ -77,7 +77,7 @@
 
 	// Invalid Authorization header is passed
 	md["authorization"] = []string{fmt.Sprintf("%s", signedKey)}
-	ctx = reqFunc(context.Background(), &md)
+	ctx = reqFunc(context.Background(), md)
 	token = ctx.Value(JWTTokenContextKey)
 	if token != nil {
 		t.Error("Context should not contain a JWT Token")
@@ -85,7 +85,7 @@
 
 	// Authorization header is correct
 	md["authorization"] = []string{fmt.Sprintf("Bearer %s", signedKey)}
-	ctx = reqFunc(context.Background(), &md)
+	ctx = reqFunc(context.Background(), md)
 	token, ok := ctx.Value(JWTTokenContextKey).(string)
 	if !ok {
 		t.Fatal("JWT Token not passed to context correctly")
diff --git a/tracing/opentracing/grpc.go b/tracing/opentracing/grpc.go
index 56eb143..fa45440 100644
--- a/tracing/opentracing/grpc.go
+++ b/tracing/opentracing/grpc.go
@@ -32,10 +32,10 @@
 // `operationName` accordingly. If no trace could be found in `req`, the Span
 // will be a trace root. The Span is incorporated in the returned Context and
 // can be retrieved with opentracing.SpanFromContext(ctx).
-func FromGRPCRequest(tracer opentracing.Tracer, operationName string, logger log.Logger) func(ctx context.Context, md *metadata.MD) context.Context {
-	return func(ctx context.Context, md *metadata.MD) context.Context {
+func FromGRPCRequest(tracer opentracing.Tracer, operationName string, logger log.Logger) func(ctx context.Context, md metadata.MD) context.Context {
+	return func(ctx context.Context, md metadata.MD) context.Context {
 		var span opentracing.Span
-		wireContext, err := tracer.Extract(opentracing.TextMap, metadataReaderWriter{md})
+		wireContext, err := tracer.Extract(opentracing.TextMap, metadataReaderWriter{&md})
 		if err != nil && err != opentracing.ErrSpanContextNotFound {
 			logger.Log("err", err)
 		}
diff --git a/tracing/opentracing/grpc_test.go b/tracing/opentracing/grpc_test.go
index 96a834f..3d07a14 100644
--- a/tracing/opentracing/grpc_test.go
+++ b/tracing/opentracing/grpc_test.go
@@ -41,7 +41,7 @@
 
 	// Use FromGRPCRequest to verify that we can join with the trace given MD.
 	fromGRPCFunc := kitot.FromGRPCRequest(tracer, "joined", logger)
-	joinCtx := fromGRPCFunc(afterCtx, &md)
+	joinCtx := fromGRPCFunc(afterCtx, md)
 	joinedSpan := opentracing.SpanFromContext(joinCtx).(*mocktracer.MockSpan)
 
 	joinedContext := joinedSpan.Context().(mocktracer.MockSpanContext)