diff --git a/okhttp-tests/src/test/java/com/squareup/okhttp/internal/tls/HostnameVerifierTest.java b/okhttp-tests/src/test/java/com/squareup/okhttp/internal/tls/HostnameVerifierTest.java
index beb2b6c..d2b4a83 100644
--- a/okhttp-tests/src/test/java/com/squareup/okhttp/internal/tls/HostnameVerifierTest.java
+++ b/okhttp-tests/src/test/java/com/squareup/okhttp/internal/tls/HostnameVerifierTest.java
@@ -24,7 +24,6 @@
 import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.SSLSession;
 import javax.security.auth.x500.X500Principal;
-import org.junit.Ignore;
 import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;
@@ -36,7 +35,7 @@
  * itself includes tests from the Apache HTTP Client test suite.
  */
 public final class HostnameVerifierTest {
-  private HostnameVerifier verifier = OkHostnameVerifier.INSTANCE;
+  private final HostnameVerifier verifier = OkHostnameVerifier.INSTANCE;
 
   @Test public void verify() throws Exception {
     FakeSSLSession session = new FakeSSLSession();
@@ -147,12 +146,7 @@
     assertFalse(verifier.verify("a.bar.com", session));
   }
 
-  /**
-   * Ignored due to incompatibilities between Android and Java on how non-ASCII
-   * subject alt names are parsed. Android fails to parse these, which means we
-   * fall back to the CN. The RI does parse them, so the CN is unused.
-   */
-  @Test @Ignore public void verifyNonAsciiSubjectAlt() throws Exception {
+  @Test public void verifyNonAsciiSubjectAlt() throws Exception {
     // CN=foo.com, subjectAlt=bar.com, subjectAlt=&#x82b1;&#x5b50;.co.jp
     // (hanako.co.jp in kanji)
     SSLSession session = session(""
@@ -182,16 +176,15 @@
         + "sWIKHYrmhCIRshUNohGXv50m2o+1w9oWmQ6Dkq7lCjfXfUB4wIbggJjpyEtbNqBt\n"
         + "j4MC2x5rfsLKKqToKmNE7pFEgqwe8//Aar1b+Qj+\n"
         + "-----END CERTIFICATE-----\n");
-    assertTrue(verifier.verify("foo.com", session));
+    // Android-changed: Ignore common name in hostname verification. http://b/70278814
+    // assertTrue(verifier.verify("foo.com", session));
+    assertFalse(verifier.verify("foo.com", session));
     assertFalse(verifier.verify("a.foo.com", session));
-    // these checks test alternative subjects. The test data contains an
-    // alternative subject starting with a japanese kanji character. This is
-    // not supported by Android because the underlying implementation from
-    // harmony follows the definition from rfc 1034 page 10 for alternative
-    // subject names. This causes the code to drop all alternative subjects.
-    // assertTrue(verifier.verify("bar.com", session));
-    // assertFalse(verifier.verify("a.bar.com", session));
-    // assertFalse(verifier.verify("a.\u82b1\u5b50.co.jp", session));
+    assertTrue(verifier.verify("bar.com", session));
+    assertFalse(verifier.verify("a.bar.com", session));
+    assertFalse(verifier.verify("a.\u82b1\u5b50.co.jp", session));
+    // Android-added: Reject non-ASCII hostnames and SANs. http://b/171980069
+    assertFalse(verifier.verify("\u82b1\u5b50.co.jp", session));
   }
 
   @Test public void verifySubjectAltOnly() throws Exception {
@@ -337,17 +330,12 @@
     // Android-changed: Ignore common name in hostname verification. http://b/70278814
     // assertTrue(verifier.verify("foo.co.jp", session));
     assertFalse(verifier.verify("foo.co.jp", session));
-    // Android-changed: Ignore common name in hostname verification. http://b/70278814
+    // Android-changed: Reject non-ASCII hostnames and SANs. http://b/171980069
     // assertTrue(verifier.verify("\u82b1\u5b50.co.jp", session));
     assertFalse(verifier.verify("\u82b1\u5b50.co.jp", session));
   }
 
-  /**
-   * Ignored due to incompatibilities between Android and Java on how non-ASCII
-   * subject alt names are parsed. Android fails to parse these, which means we
-   * fall back to the CN. The RI does parse them, so the CN is unused.
-   */
-  @Test @Ignore public void testWilcardNonAsciiSubjectAlt() throws Exception {
+  @Test public void testWilcardNonAsciiSubjectAlt() throws Exception {
     // CN=*.foo.com, subjectAlt=*.bar.com, subjectAlt=*.&#x82b1;&#x5b50;.co.jp
     // (*.hanako.co.jp in kanji)
     SSLSession session = session(""
@@ -378,19 +366,22 @@
         + "pgJsDbJtZfHnV1nd3M6zOtQPm1TIQpNmMMMd/DPrGcUQerD3\n"
         + "-----END CERTIFICATE-----\n");
     // try the foo.com variations
-    assertTrue(verifier.verify("foo.com", session));
-    assertTrue(verifier.verify("www.foo.com", session));
-    assertTrue(verifier.verify("\u82b1\u5b50.foo.com", session));
+    // BEGIN Android-changed: Ignore common name in hostname verification. http://b/70278814
+    // assertTrue(verifier.verify("foo.com", session));
+    // assertTrue(verifier.verify("www.foo.com", session));
+    // assertTrue(verifier.verify("\u82b1\u5b50.foo.com", session));
+    assertFalse(verifier.verify("foo.com", session));
+    assertFalse(verifier.verify("www.foo.com", session));
+    assertFalse(verifier.verify("\u82b1\u5b50.foo.com", session));
+    // END Android-changed: Ignore common name in hostname verification. http://b/70278814
     assertFalse(verifier.verify("a.b.foo.com", session));
-    // these checks test alternative subjects. The test data contains an
-    // alternative subject starting with a japanese kanji character. This is
-    // not supported by Android because the underlying implementation from
-    // harmony follows the definition from rfc 1034 page 10 for alternative
-    // subject names. This causes the code to drop all alternative subjects.
-    // assertFalse(verifier.verify("bar.com", session));
-    // assertTrue(verifier.verify("www.bar.com", session));
+    // these checks test alternative subjects.
+    assertFalse(verifier.verify("bar.com", session));
+    assertTrue(verifier.verify("www.bar.com", session));
+    // Android-changed: Reject non-ASCII hostnames and SANs. http://b/171980069
     // assertTrue(verifier.verify("\u82b1\u5b50.bar.com", session));
-    // assertTrue(verifier.verify("a.b.bar.com", session));
+    assertFalse(verifier.verify("\u82b1\u5b50.bar.com", session));
+    assertFalse(verifier.verify("a.b.bar.com", session));
   }
 
   @Test public void subjectAltUsesLocalDomainAndIp() throws Exception {
@@ -558,6 +549,14 @@
     assertFalse(OkHostnameVerifier.verifyAsIpAddress("www.nintendo.co.jp"));
   }
 
+  @Test public void isPrintableAscii() {
+    assertTrue(OkHostnameVerifier.isPrintableAscii("foo-bar_baz.com"));
+    assertTrue(OkHostnameVerifier.isPrintableAscii("FoO-bAr_BaZ.cOm"));
+    assertFalse(OkHostnameVerifier.isPrintableAscii("Føø-bAr_BaZ.cøm"));
+    // Char 0xc0 (capital A with grave accent in ISO 8859-1) fits in 8 bits but not 7.
+    assertFalse(OkHostnameVerifier.isPrintableAscii("\u00c0.com"));
+  }
+
   private X509Certificate certificate(String certificate) throws Exception {
     return (X509Certificate) CertificateFactory.getInstance("X.509").generateCertificate(
         new ByteArrayInputStream(certificate.getBytes(Util.UTF_8)));
diff --git a/okhttp/src/main/java/com/squareup/okhttp/internal/tls/OkHostnameVerifier.java b/okhttp/src/main/java/com/squareup/okhttp/internal/tls/OkHostnameVerifier.java
index c947d7d..399614b 100644
--- a/okhttp/src/main/java/com/squareup/okhttp/internal/tls/OkHostnameVerifier.java
+++ b/okhttp/src/main/java/com/squareup/okhttp/internal/tls/OkHostnameVerifier.java
@@ -94,6 +94,11 @@
    * Returns true if {@code certificate} matches {@code hostName}.
    */
   private boolean verifyHostName(String hostName, X509Certificate certificate) {
+    // BEGIN Android-added: Reject non-ASCII hostnames and SANs. http://b/171980069
+    if (!isPrintableAscii(hostName)) {
+      return false;
+    }
+    // END Android-added: Reject non-ASCII hostnames and SANs. http://b/171980069
     hostName = hostName.toLowerCase(Locale.US);
     boolean hasDns = false;
     List<String> altNames = getSubjectAltNames(certificate, ALT_DNS_NAME);
@@ -196,6 +201,11 @@
     }
     // hostName and pattern are now absolute domain names.
 
+    // BEGIN Android-added: Reject non-ASCII hostnames and SANs. http://b/171980069
+    if (!isPrintableAscii(pattern)) {
+      return false;
+    }
+    // END Android-added: Reject non-ASCII hostnames and SANs. http://b/171980069
     pattern = pattern.toLowerCase(Locale.US);
     // hostName and pattern are now in lower case -- domain names are case-insensitive.
 
@@ -252,4 +262,25 @@
     // hostName matches pattern
     return true;
   }
+
+  // BEGIN Android-added: Reject non-ASCII hostnames and SANs. http://b/171980069
+  /**
+   * Returns true if the  input string contains only printable 7-bit ASCII
+   * characters, otherwise false.
+   */
+  private static final char DEL = 127;
+  static boolean isPrintableAscii(String input) {
+    if (input == null) {
+      return false;
+    }
+    for (char c : input.toCharArray()) {
+      // Space is illegal in a DNS name. DEL and anything less than space is non-printing so
+      // also illegal. Anything greater than DEL is not 7-bit.
+      if (c <= ' ' || c >= DEL) {
+        return false;
+      }
+    }
+    return true;
+  }
+  // END Android-added: Reject non-ASCII hostnames and SANs. http://b/171980069
 }