diff --git a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/userinfo/OAuth2UserRequestEntityConverter.java b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/userinfo/OAuth2UserRequestEntityConverter.java
index 777ac39004..38e9ad5dc8 100644
--- a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/userinfo/OAuth2UserRequestEntityConverter.java
+++ b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/userinfo/OAuth2UserRequestEntityConverter.java
@@ -60,7 +60,7 @@ public class OAuth2UserRequestEntityConverter implements Converter<OAuth2UserReq
 			httpMethod = HttpMethod.POST;
 		}
 		HttpHeaders headers = new HttpHeaders();
-		headers.setAccept(Collections.singletonList(MediaType.APPLICATION_JSON_UTF8));
+		headers.setAccept(Collections.singletonList(MediaType.APPLICATION_JSON));
 		URI uri = UriComponentsBuilder.fromUriString(clientRegistration.getProviderDetails().getUserInfoEndpoint().getUri())
 				.build()
 				.toUri();
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/oidc/userinfo/OidcUserServiceTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/oidc/userinfo/OidcUserServiceTests.java
index 786298d7f6..6a87b4e49f 100644
--- a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/oidc/userinfo/OidcUserServiceTests.java
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/oidc/userinfo/OidcUserServiceTests.java
@@ -316,7 +316,7 @@ public class OidcUserServiceTests {
 
 		this.userService.loadUser(new OidcUserRequest(this.clientRegistration, this.accessToken, this.idToken));
 		assertThat(this.server.takeRequest(1, TimeUnit.SECONDS).getHeader(HttpHeaders.ACCEPT))
-				.isEqualTo(MediaType.APPLICATION_JSON_UTF8_VALUE);
+				.isEqualTo(MediaType.APPLICATION_JSON_VALUE);
 	}
 
 	// gh-5500
@@ -341,7 +341,7 @@ public class OidcUserServiceTests {
 		this.userService.loadUser(new OidcUserRequest(this.clientRegistration, this.accessToken, this.idToken));
 		RecordedRequest request = this.server.takeRequest();
 		assertThat(request.getMethod()).isEqualTo(HttpMethod.GET.name());
-		assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo(MediaType.APPLICATION_JSON_UTF8_VALUE);
+		assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo(MediaType.APPLICATION_JSON_VALUE);
 		assertThat(request.getHeader(HttpHeaders.AUTHORIZATION)).isEqualTo("Bearer " + this.accessToken.getTokenValue());
 	}
 
@@ -367,7 +367,7 @@ public class OidcUserServiceTests {
 		this.userService.loadUser(new OidcUserRequest(this.clientRegistration, this.accessToken, this.idToken));
 		RecordedRequest request = this.server.takeRequest();
 		assertThat(request.getMethod()).isEqualTo(HttpMethod.POST.name());
-		assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo(MediaType.APPLICATION_JSON_UTF8_VALUE);
+		assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo(MediaType.APPLICATION_JSON_VALUE);
 		assertThat(request.getHeader(HttpHeaders.CONTENT_TYPE)).contains(MediaType.APPLICATION_FORM_URLENCODED_VALUE);
 		assertThat(request.getBody().readUtf8()).isEqualTo("access_token=" + this.accessToken.getTokenValue());
 	}
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/userinfo/DefaultOAuth2UserServiceTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/userinfo/DefaultOAuth2UserServiceTests.java
index dd5a5dd891..a2fc4733bd 100644
--- a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/userinfo/DefaultOAuth2UserServiceTests.java
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/userinfo/DefaultOAuth2UserServiceTests.java
@@ -277,7 +277,7 @@ public class DefaultOAuth2UserServiceTests {
 
 		this.userService.loadUser(new OAuth2UserRequest(this.clientRegistration, this.accessToken));
 		assertThat(this.server.takeRequest(1, TimeUnit.SECONDS).getHeader(HttpHeaders.ACCEPT))
-				.isEqualTo(MediaType.APPLICATION_JSON_UTF8_VALUE);
+				.isEqualTo(MediaType.APPLICATION_JSON_VALUE);
 	}
 
 	// gh-5500
@@ -303,7 +303,7 @@ public class DefaultOAuth2UserServiceTests {
 		this.userService.loadUser(new OAuth2UserRequest(this.clientRegistration, this.accessToken));
 		RecordedRequest request = this.server.takeRequest();
 		assertThat(request.getMethod()).isEqualTo(HttpMethod.GET.name());
-		assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo(MediaType.APPLICATION_JSON_UTF8_VALUE);
+		assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo(MediaType.APPLICATION_JSON_VALUE);
 		assertThat(request.getHeader(HttpHeaders.AUTHORIZATION)).isEqualTo("Bearer " + this.accessToken.getTokenValue());
 	}
 
@@ -330,7 +330,7 @@ public class DefaultOAuth2UserServiceTests {
 		this.userService.loadUser(new OAuth2UserRequest(this.clientRegistration, this.accessToken));
 		RecordedRequest request = this.server.takeRequest();
 		assertThat(request.getMethod()).isEqualTo(HttpMethod.POST.name());
-		assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo(MediaType.APPLICATION_JSON_UTF8_VALUE);
+		assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo(MediaType.APPLICATION_JSON_VALUE);
 		assertThat(request.getHeader(HttpHeaders.CONTENT_TYPE)).contains(MediaType.APPLICATION_FORM_URLENCODED_VALUE);
 		assertThat(request.getBody().readUtf8()).isEqualTo("access_token=" + this.accessToken.getTokenValue());
 	}
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/userinfo/OAuth2UserRequestEntityConverterTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/userinfo/OAuth2UserRequestEntityConverterTests.java
index b6ca08140a..d6560d717a 100644
--- a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/userinfo/OAuth2UserRequestEntityConverterTests.java
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/userinfo/OAuth2UserRequestEntityConverterTests.java
@@ -56,7 +56,7 @@ public class OAuth2UserRequestEntityConverterTests {
 				clientRegistration.getProviderDetails().getUserInfoEndpoint().getUri());
 
 		HttpHeaders headers = requestEntity.getHeaders();
-		assertThat(headers.getAccept()).contains(MediaType.APPLICATION_JSON_UTF8);
+		assertThat(headers.getAccept()).contains(MediaType.APPLICATION_JSON);
 		assertThat(headers.getFirst(HttpHeaders.AUTHORIZATION)).isEqualTo(
 				"Bearer " + userRequest.getAccessToken().getTokenValue());
 	}
@@ -77,7 +77,7 @@ public class OAuth2UserRequestEntityConverterTests {
 				clientRegistration.getProviderDetails().getUserInfoEndpoint().getUri());
 
 		HttpHeaders headers = requestEntity.getHeaders();
-		assertThat(headers.getAccept()).contains(MediaType.APPLICATION_JSON_UTF8);
+		assertThat(headers.getAccept()).contains(MediaType.APPLICATION_JSON);
 		assertThat(headers.getContentType()).isEqualTo(
 				MediaType.valueOf(APPLICATION_FORM_URLENCODED_VALUE + ";charset=UTF-8"));