diff --git a/core/src/main/java/io/grpc/internal/GrpcUtil.java b/core/src/main/java/io/grpc/internal/GrpcUtil.java
index b2b16608e4..f75193be8c 100644
--- a/core/src/main/java/io/grpc/internal/GrpcUtil.java
+++ b/core/src/main/java/io/grpc/internal/GrpcUtil.java
@@ -31,6 +31,7 @@
 
 package io.grpc.internal;
 
+import static com.google.common.base.Preconditions.checkArgument;
 import static io.grpc.Status.Code.CANCELLED;
 import static io.grpc.Status.Code.DEADLINE_EXCEEDED;
 
@@ -319,10 +320,6 @@ public final class GrpcUtil {
     } catch (URISyntaxException ex) {
       throw new IllegalArgumentException("Invalid authority: " + authority, ex);
     }
-    if (uri.getUserInfo() != null) {
-      throw new IllegalArgumentException(
-          "Userinfo must not be present on authority: " + authority);
-    }
     return uri;
   }
 
@@ -333,7 +330,10 @@ public final class GrpcUtil {
    * @return the {@code authority} provided
    */
   public static String checkAuthority(String authority) {
-    authorityToUri(authority);
+    URI uri = authorityToUri(authority);
+    checkArgument(uri.getHost() != null, "No host in authority '%s'", authority);
+    checkArgument(uri.getUserInfo() == null,
+        "Userinfo must not be present on authority: '%s'", authority);
     return authority;
   }
 
diff --git a/core/src/test/java/io/grpc/internal/GrpcUtilTest.java b/core/src/test/java/io/grpc/internal/GrpcUtilTest.java
index 4338489651..50e651fef7 100644
--- a/core/src/test/java/io/grpc/internal/GrpcUtilTest.java
+++ b/core/src/test/java/io/grpc/internal/GrpcUtilTest.java
@@ -40,13 +40,18 @@ import static org.junit.Assert.assertTrue;
 import io.grpc.Status;
 import io.grpc.internal.GrpcUtil.Http2Error;
 
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
 
 /** Unit tests for {@link GrpcUtil}. */
 @RunWith(JUnit4.class)
 public class GrpcUtilTest {
+
+  @Rule public final ExpectedException thrown = ExpectedException.none();
+
   @Test
   public void http2ErrorForCode() {
     // Try edge cases manually, to make the test obviously correct for important cases.
@@ -117,4 +122,56 @@ public class GrpcUtilTest {
   public void contentTypeShouldNotBeValid() {
     assertFalse(GrpcUtil.isGrpcContentType("application/bad"));
   }
+
+  @Test
+  public void checkAuthority_failsOnNull() {
+    thrown.expect(NullPointerException.class);
+
+    GrpcUtil.checkAuthority(null);
+  }
+
+  @Test
+  public void checkAuthority_succeedsOnHostAndPort() {
+    String actual = GrpcUtil.checkAuthority("valid:1234");
+
+    assertEquals("valid:1234", actual);
+  }
+
+  @Test
+  public void checkAuthority_succeedsOnHost() {
+    String actual = GrpcUtil.checkAuthority("valid");
+
+    assertEquals("valid", actual);
+  }
+
+  @Test
+  public void checkAuthority_succeedsOnIpV6() {
+    String actual = GrpcUtil.checkAuthority("[::1]");
+
+    assertEquals("[::1]", actual);
+  }
+
+  @Test
+  public void checkAuthority_failsOnInvalidAuthority() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Invalid authority");
+
+    GrpcUtil.checkAuthority("[ : : 1]");
+  }
+
+  @Test
+  public void checkAuthority_failsOnInvalidHost() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("No host in authority");
+
+    GrpcUtil.checkAuthority("bad_host");
+  }
+
+  @Test
+  public void checkAuthority_userInfoNotAllowed() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Userinfo");
+
+    GrpcUtil.checkAuthority("foo@valid");
+  }
 }