diff --git a/api/server/middleware/middleware.go b/api/server/middleware/middleware.go
index d935fa265ffe..b85e59e895b6 100644
--- a/api/server/middleware/middleware.go
+++ b/api/server/middleware/middleware.go
@@ -50,7 +50,7 @@ func ContentTypeHandler(acceptedMediaTypes []string) mux.MiddlewareFunc {
 
 			accepted := false
 			for _, acceptedType := range acceptedMediaTypes {
-				if strings.TrimSpace(contentType) == strings.TrimSpace(acceptedType) {
+				if strings.Contains(strings.TrimSpace(contentType), strings.TrimSpace(acceptedType)) {
 					accepted = true
 					break
 				}
diff --git a/api/server/middleware/middleware_test.go b/api/server/middleware/middleware_test.go
index 5869de26b003..3b899d74a59e 100644
--- a/api/server/middleware/middleware_test.go
+++ b/api/server/middleware/middleware_test.go
@@ -96,6 +96,11 @@ func TestContentTypeHandler(t *testing.T) {
 			expectedStatusCode: http.StatusOK,
 			isGet:              true,
 		},
+		{
+			name:               "Content type contains charset is ok",
+			contentType:        "application/json; charset=utf-8",
+			expectedStatusCode: http.StatusOK,
+		},
 	}
 
 	for _, tt := range tests {
diff --git a/validator/client/beacon-api/json_rest_handler.go b/validator/client/beacon-api/json_rest_handler.go
index 890a10e26be6..0877bff1019b 100644
--- a/validator/client/beacon-api/json_rest_handler.go
+++ b/validator/client/beacon-api/json_rest_handler.go
@@ -109,7 +109,7 @@ func decodeResp(httpResp *http.Response, resp interface{}) error {
 		return errors.Wrapf(err, "failed to read response body for %s", httpResp.Request.URL)
 	}
 
-	if httpResp.Header.Get("Content-Type") != api.JsonMediaType {
+	if !strings.Contains(httpResp.Header.Get("Content-Type"), api.JsonMediaType) {
 		// 2XX codes are a success
 		if strings.HasPrefix(httpResp.Status, "2") {
 			return nil
diff --git a/validator/client/beacon-api/json_rest_handler_test.go b/validator/client/beacon-api/json_rest_handler_test.go
index d28729eee652..264bff59a60a 100644
--- a/validator/client/beacon-api/json_rest_handler_test.go
+++ b/validator/client/beacon-api/json_rest_handler_test.go
@@ -99,7 +99,16 @@ func Test_decodeResp(t *testing.T) {
 	type j struct {
 		Foo string `json:"foo"`
 	}
-
+	t.Run("200 JSON with charset", func(t *testing.T) {
+		body := bytes.Buffer{}
+		r := &http.Response{
+			Status:     "200",
+			StatusCode: http.StatusOK,
+			Body:       io.NopCloser(&body),
+			Header:     map[string][]string{"Content-Type": {"application/json; charset=utf-8"}},
+		}
+		require.NoError(t, decodeResp(r, nil))
+	})
 	t.Run("200 non-JSON", func(t *testing.T) {
 		body := bytes.Buffer{}
 		r := &http.Response{