diff --git a/impl/extension/rest/src/main/java/br/gov/frameworkdemoiselle/internal/implementation/AuthenticationExceptionMapper.java b/impl/extension/rest/src/main/java/br/gov/frameworkdemoiselle/internal/implementation/AuthenticationExceptionMapper.java
index a45432f..2db5055 100644
--- a/impl/extension/rest/src/main/java/br/gov/frameworkdemoiselle/internal/implementation/AuthenticationExceptionMapper.java
+++ b/impl/extension/rest/src/main/java/br/gov/frameworkdemoiselle/internal/implementation/AuthenticationExceptionMapper.java
@@ -7,11 +7,12 @@ import javax.ws.rs.ext.ExceptionMapper;
 import javax.ws.rs.ext.Provider;
 
 import br.gov.frameworkdemoiselle.security.AuthenticationException;
+
 @Provider
 public class AuthenticationExceptionMapper implements ExceptionMapper<AuthenticationException> {
 
 	@Override
 	public Response toResponse(AuthenticationException exception) {
-		return Response.status(SC_UNAUTHORIZED).entity(exception.getMessage()).build();
+		return Response.status(SC_UNAUTHORIZED).entity(exception.getMessage()).type("text/plain").build();
 	}
 }
--
libgit2 0.21.2