diff --git a/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java b/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
index e70c175b3c..e858062dd1 100644
--- a/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
+++ b/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
@@ -384,11 +384,7 @@ public void testBitSetDeserialization() {
   public void testDefaultDateSerialization() {
     Date now = new Date(1315806903103L);
     String json = gson.toJson(now);
-    if (JavaVersion.isJava9OrLater()) {
-      assertThat(json).isEqualTo("\"Sep 11, 2011, 10:55:03 PM\"");
-    } else {
-      assertThat(json).isEqualTo("\"Sep 11, 2011 10:55:03 PM\"");
-    }
+    assertThat(json).matches("\"Sep 11, 2011,? 10:55:03\\hPM\"");
   }
 
   @Test
@@ -420,11 +416,7 @@ public void testDefaultDateSerializationUsingBuilder() {
     Gson gson = new GsonBuilder().create();
     Date now = new Date(1315806903103L);
     String json = gson.toJson(now);
-    if (JavaVersion.isJava9OrLater()) {
-      assertThat(json).isEqualTo("\"Sep 11, 2011, 10:55:03 PM\"");
-    } else {
-      assertThat(json).isEqualTo("\"Sep 11, 2011 10:55:03 PM\"");
-    }
+    assertThat(json).matches("\"Sep 11, 2011,? 10:55:03\\hPM\"");
   }
 
   @Test
diff --git a/gson/src/test/java/com/google/gson/functional/ObjectTest.java b/gson/src/test/java/com/google/gson/functional/ObjectTest.java
index b0de9da48d..e0efd94dee 100644
--- a/gson/src/test/java/com/google/gson/functional/ObjectTest.java
+++ b/gson/src/test/java/com/google/gson/functional/ObjectTest.java
@@ -570,11 +570,8 @@ static final class Product {
   public void testDateAsMapObjectField() {
     HasObjectMap a = new HasObjectMap();
     a.map.put("date", new Date(0));
-    if (JavaVersion.isJava9OrLater()) {
-      assertThat(gson.toJson(a)).isEqualTo("{\"map\":{\"date\":\"Dec 31, 1969, 4:00:00 PM\"}}");
-    } else {
-      assertThat(gson.toJson(a)).isEqualTo("{\"map\":{\"date\":\"Dec 31, 1969 4:00:00 PM\"}}");
-    }
+    assertThat(gson.toJson(a))
+        .matches("\\{\"map\":\\{\"date\":\"Dec 31, 1969,? 4:00:00\\hPM\"\\}\\}");
   }
 
   static class HasObjectMap {
diff --git a/gson/src/test/java/com/google/gson/internal/bind/DefaultDateTypeAdapterTest.java b/gson/src/test/java/com/google/gson/internal/bind/DefaultDateTypeAdapterTest.java
index 2034e38fc6..835bc9dd49 100644
--- a/gson/src/test/java/com/google/gson/internal/bind/DefaultDateTypeAdapterTest.java
+++ b/gson/src/test/java/com/google/gson/internal/bind/DefaultDateTypeAdapterTest.java
@@ -58,21 +58,22 @@ private void assertFormattingAlwaysEmitsUsLocale(Locale locale) {
     Locale defaultLocale = Locale.getDefault();
     Locale.setDefault(locale);
     try {
-      String afterYearSep = JavaVersion.isJava9OrLater() ? ", " : " ";
-      String afterYearLongSep = JavaVersion.isJava9OrLater() ? " at " : " ";
-      String utcFull = JavaVersion.isJava9OrLater() ? "Coordinated Universal Time" : "UTC";
-      assertFormatted(String.format("Jan 1, 1970%s12:00:00 AM", afterYearSep),
-          DateType.DATE.createDefaultsAdapterFactory());
+      // The patterns here attempt to accommodate minor date-time formatting differences between JDK
+      // versions. Ideally Gson would serialize in a way that is independent of the JDK version.
+      // Note: \h means "horizontal space", because some JDK versions use Narrow No Break Space
+      // (U+202F) before the AM or PM indication.
+      String utcFull = "(Coordinated Universal Time|UTC)";
+      assertFormatted("Jan 1, 1970,? 12:00:00\\hAM", DateType.DATE.createDefaultsAdapterFactory());
       assertFormatted("1/1/70", DateType.DATE.createAdapterFactory(DateFormat.SHORT));
       assertFormatted("Jan 1, 1970", DateType.DATE.createAdapterFactory(DateFormat.MEDIUM));
       assertFormatted("January 1, 1970", DateType.DATE.createAdapterFactory(DateFormat.LONG));
-      assertFormatted(String.format("1/1/70%s12:00 AM", afterYearSep),
+      assertFormatted("1/1/70,? 12:00\\hAM",
           DateType.DATE.createAdapterFactory(DateFormat.SHORT, DateFormat.SHORT));
-      assertFormatted(String.format("Jan 1, 1970%s12:00:00 AM", afterYearSep),
+      assertFormatted("Jan 1, 1970,? 12:00:00\\hAM",
           DateType.DATE.createAdapterFactory(DateFormat.MEDIUM, DateFormat.MEDIUM));
-      assertFormatted(String.format("January 1, 1970%s12:00:00 AM UTC", afterYearLongSep),
+      assertFormatted("January 1, 1970(,| at)? 12:00:00\\hAM UTC",
           DateType.DATE.createAdapterFactory(DateFormat.LONG, DateFormat.LONG));
-      assertFormatted(String.format("Thursday, January 1, 1970%s12:00:00 AM %s", afterYearLongSep, utcFull),
+      assertFormatted("Thursday, January 1, 1970(,| at)? 12:00:00\\hAM " + utcFull,
           DateType.DATE.createAdapterFactory(DateFormat.FULL, DateFormat.FULL));
     } finally {
       TimeZone.setDefault(defaultTimeZone);
@@ -150,9 +151,7 @@ public void testFormatUsesDefaultTimezone() throws Exception {
     Locale defaultLocale = Locale.getDefault();
     Locale.setDefault(Locale.US);
     try {
-      String afterYearSep = JavaVersion.isJava9OrLater() ? ", " : " ";
-      assertFormatted(String.format("Dec 31, 1969%s4:00:00 PM", afterYearSep),
-          DateType.DATE.createDefaultsAdapterFactory());
+      assertFormatted("Dec 31, 1969,? 4:00:00\\hPM", DateType.DATE.createDefaultsAdapterFactory());
       assertParsed("Dec 31, 1969 4:00:00 PM", DateType.DATE.createDefaultsAdapterFactory());
     } finally {
       TimeZone.setDefault(defaultTimeZone);
@@ -222,9 +221,10 @@ private static TypeAdapter<Date> dateAdapter(TypeAdapterFactory adapterFactory)
     return adapter;
   }
 
-  private static void assertFormatted(String formatted, TypeAdapterFactory adapterFactory) {
+  private static void assertFormatted(String formattedPattern, TypeAdapterFactory adapterFactory) {
     TypeAdapter<Date> adapter = dateAdapter(adapterFactory);
-    assertThat(adapter.toJson(new Date(0))).isEqualTo(toLiteral(formatted));
+    String json = adapter.toJson(new Date(0));
+    assertThat(json).matches(toLiteral(formattedPattern));
   }
 
   @SuppressWarnings("UndefinedEquals")
diff --git a/gson/src/test/java/com/google/gson/internal/sql/SqlTypesGsonTest.java b/gson/src/test/java/com/google/gson/internal/sql/SqlTypesGsonTest.java
index b04c56ab34..8233275c37 100644
--- a/gson/src/test/java/com/google/gson/internal/sql/SqlTypesGsonTest.java
+++ b/gson/src/test/java/com/google/gson/internal/sql/SqlTypesGsonTest.java
@@ -113,11 +113,10 @@ public void testDefaultSqlTimeDeserialization() {
   public void testDefaultSqlTimestampSerialization() {
     Timestamp now = new java.sql.Timestamp(1259875082000L);
     String json = gson.toJson(now);
-    if (JavaVersion.isJava9OrLater()) {
-      assertThat(json).isEqualTo("\"Dec 3, 2009, 1:18:02 PM\"");
-    } else {
-      assertThat(json).isEqualTo("\"Dec 3, 2009 1:18:02 PM\"");
-    }
+    // The exact format of the serialized date-time string depends on the JDK version. The pattern
+    // here allows for an optional comma after the date, and what might be U+202F (Narrow No-Break
+    // Space) before "PM".
+    assertThat(json).matches("\"Dec 3, 2009,? 1:18:02\\hPM\"");
   }
 
   @Test