diff --git a/common/src/main/java/org/keycloak/common/util/KeycloakUriBuilder.java b/common/src/main/java/org/keycloak/common/util/KeycloakUriBuilder.java
index ed00aeac04..dd5590ef9a 100755
--- a/common/src/main/java/org/keycloak/common/util/KeycloakUriBuilder.java
+++ b/common/src/main/java/org/keycloak/common/util/KeycloakUriBuilder.java
@@ -429,7 +429,7 @@ public class KeycloakUriBuilder {
                 if ("".equals(host)) throw new RuntimeException("empty host name");
                 replaceParameter(paramMap, fromEncodedMap, isTemplate, host, buffer, encodeSlash);
             }
-            if (port != -1 && (scheme == null || (scheme.equals("http") && port != 80) || (scheme.equals("https") && port != 443)) ) {
+            if (port != -1 && !(("http".equals(scheme) && port == 80) || ("https".equals(scheme) && port == 443))) {
                 buffer.append(":").append(Integer.toString(port));
             }
         } else if (authority != null) {
diff --git a/common/src/test/java/org/keycloak/common/util/KeycloakUriBuilderTest.java b/common/src/test/java/org/keycloak/common/util/KeycloakUriBuilderTest.java
new file mode 100644
index 0000000000..c4cdb8e260
--- /dev/null
+++ b/common/src/test/java/org/keycloak/common/util/KeycloakUriBuilderTest.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2021 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package org.keycloak.common.util;
+
+import java.util.Collections;
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * @author rmartinc
+ */
+public class KeycloakUriBuilderTest {
+
+    @Test
+    public void test() {
+        Assert.assertEquals("http://localhost:8080/path?attr1=value1&attr2=value2",
+                KeycloakUriBuilder.fromUri("http://localhost:8080/path?attr1=value1&attr2=value2")
+                        .build().toString());
+
+        Assert.assertEquals("http://localhost/path?attr1=value1&attr2=value2",
+                KeycloakUriBuilder.fromUri("http://localhost:80")
+                        .path("path")
+                        .queryParam("attr1", "value1")
+                        .queryParam("attr2", "value2")
+                        .build().toString());
+
+        Assert.assertEquals("unknown://localhost:9000/path",
+                KeycloakUriBuilder.fromUri("unknown://localhost:9000/path").build().toString());
+
+        Assert.assertEquals("https://localhost/path?attr1=value1",
+                KeycloakUriBuilder.fromUri("https://{hostname}:443/path?attr1={value}")
+                        .build("localhost", "value1").toString());
+
+        Assert.assertEquals("https://localhost:8443/path?attr1=value1",
+                KeycloakUriBuilder.fromUri("https://localhost:8443/path?attr1={value}")
+                        .buildFromMap(Collections.singletonMap("value", "value1")).toString());
+    }
+}