diff --git a/oauth2/oauth2-resource-server/src/main/java/org/springframework/security/oauth2/server/resource/web/server/ServerBearerTokenAuthenticationConverter.java b/oauth2/oauth2-resource-server/src/main/java/org/springframework/security/oauth2/server/resource/web/server/ServerBearerTokenAuthenticationConverter.java
index 855d1d43e11..15c3b45caa9 100644
--- a/oauth2/oauth2-resource-server/src/main/java/org/springframework/security/oauth2/server/resource/web/server/ServerBearerTokenAuthenticationConverter.java
+++ b/oauth2/oauth2-resource-server/src/main/java/org/springframework/security/oauth2/server/resource/web/server/ServerBearerTokenAuthenticationConverter.java
@@ -43,7 +43,9 @@
  */
 public class ServerBearerTokenAuthenticationConverter
 		implements ServerAuthenticationConverter {
-	private static final Pattern authorizationPattern = Pattern.compile("^Bearer (?<token>[a-zA-Z0-9-._~+/]+)=*$");
+	private static final Pattern authorizationPattern = Pattern.compile(
+		"^Bearer (?<token>[a-zA-Z0-9-._~+/]+)=*$",
+		Pattern.CASE_INSENSITIVE);
 
 	private boolean allowUriQueryParameter = false;
 
@@ -85,7 +87,7 @@ public void setAllowUriQueryParameter(boolean allowUriQueryParameter) {
 
 	private static String resolveFromAuthorizationHeader(HttpHeaders headers) {
 		String authorization = headers.getFirst(HttpHeaders.AUTHORIZATION);
-		if (StringUtils.hasText(authorization) && authorization.startsWith("Bearer")) {
+		if (StringUtils.startsWithIgnoreCase(authorization, "bearer")) {
 			Matcher matcher = authorizationPattern.matcher(authorization);
 
 			if ( !matcher.matches() ) {
diff --git a/oauth2/oauth2-resource-server/src/test/java/org/springframework/security/oauth2/server/resource/web/server/ServerBearerTokenAuthenticationConverterTests.java b/oauth2/oauth2-resource-server/src/test/java/org/springframework/security/oauth2/server/resource/web/server/ServerBearerTokenAuthenticationConverterTests.java
index f4b9a099676..6aacc299135 100644
--- a/oauth2/oauth2-resource-server/src/test/java/org/springframework/security/oauth2/server/resource/web/server/ServerBearerTokenAuthenticationConverterTests.java
+++ b/oauth2/oauth2-resource-server/src/test/java/org/springframework/security/oauth2/server/resource/web/server/ServerBearerTokenAuthenticationConverterTests.java
@@ -52,6 +52,15 @@ public void resolveWhenValidHeaderIsPresentThenTokenIsResolved() {
 		assertThat(convertToToken(request).getToken()).isEqualTo(TEST_TOKEN);
 	}
 
+	@Test
+	public void resolveWhenLowercaseHeaderIsPresentThenTokenIsResolved() {
+		MockServerHttpRequest.BaseBuilder<?> request = MockServerHttpRequest
+				.get("/")
+				.header(HttpHeaders.AUTHORIZATION, "bearer " + TEST_TOKEN);
+
+		assertThat(convertToToken(request).getToken()).isEqualTo(TEST_TOKEN);
+	}
+
 	@Test
 	public void resolveWhenNoHeaderIsPresentThenTokenIsNotResolved() {
 		MockServerHttpRequest.BaseBuilder<?> request = MockServerHttpRequest