diff --git a/android/PhoneticStringUtilsTest.cpp b/android/PhoneticStringUtilsTest.cpp
index ae9df2a..0541007 100644
--- a/android/PhoneticStringUtilsTest.cpp
+++ b/android/PhoneticStringUtilsTest.cpp
@@ -32,6 +32,7 @@
   void testGetCodePointFromUtf8();
   void testGetPhoneticallySortableCodePointAscii();
   void testGetPhoneticallySortableCodePointKana();
+  void testGetPhoneticallySortableCodePointWhitespaceOnly();
   void testGetPhoneticallySortableCodePointSimpleCompare();
   void testGetUtf8FromCodePoint();
   void testGetPhoneticallySortableString();
@@ -66,6 +67,7 @@
   DoOneTest(&TestExecutor::testGetCodePointFromUtf8);
   DoOneTest(&TestExecutor::testGetPhoneticallySortableCodePointAscii);
   DoOneTest(&TestExecutor::testGetPhoneticallySortableCodePointKana);
+  DoOneTest(&TestExecutor::testGetPhoneticallySortableCodePointWhitespaceOnly);
   DoOneTest(&TestExecutor::testGetPhoneticallySortableCodePointSimpleCompare);
   DoOneTest(&TestExecutor::testGetUtf8FromCodePoint);
   DoOneTest(&TestExecutor::testGetPhoneticallySortableString);
@@ -121,6 +123,8 @@
                                                     &next_is_consumed);
     if (halfwidth[i] < 0) {
       printf("returned value become negative at 0x%04X", codepoint);
+      m_success = false;
+      return;
     }
     if (next_is_consumed) {
       printf("next_is_consumed become true at 0x%04X", codepoint);
@@ -133,6 +137,8 @@
                                                     &next_is_consumed);
     if (fullwidth[i] < 0) {
       printf("returned value become negative at 0x%04X", codepoint);
+      m_success = false;
+      return;
     }
     if (next_is_consumed) {
       printf("next_is_consumed become true at 0x%04X", codepoint);
@@ -158,6 +164,8 @@
                                                    &next_is_consumed);
     if (hiragana[i] < 0) {
       printf("returned value become negative at 0x%04X", codepoint);
+      m_success = false;
+      return;
     }
     if (next_is_consumed) {
       printf("next_is_consumed become true at 0x%04X", codepoint);
@@ -171,6 +179,8 @@
                                                    &next_is_consumed);
     if (fullwidth_katakana[i] < 0) {
       printf("returned value become negative at 0x%04X", codepoint);
+      m_success = false;
+      return;
     }
     if (next_is_consumed) {
       printf("next_is_consumed become true at 0x%04X", codepoint);
@@ -221,6 +231,19 @@
   }
 }
 
+void TestExecutor::testGetPhoneticallySortableCodePointWhitespaceOnly() {
+  printf("testGetPhoneticallySortableCodePointWhitespaceOnly");
+  // Halfwidth space
+  int result = GetPhoneticallySortableCodePoint(0x0020, 0x0061, NULL);
+  ASSERT_EQ_VALUE(result, -1);
+  // Fullwidth space
+  result = GetPhoneticallySortableCodePoint(0x3000, 0x0062, NULL);
+  ASSERT_EQ_VALUE(result, -1);
+  // tab
+  result = GetPhoneticallySortableCodePoint(0x0009, 0x0062, NULL);
+  ASSERT_EQ_VALUE(result, -1);
+}
+
 void TestExecutor::testGetPhoneticallySortableCodePointSimpleCompare() {
   printf("testGetPhoneticallySortableCodePointSimpleCompare()\n");
 
@@ -345,6 +368,9 @@
   EXPECT_EQ_UTF8_UTF8(
       "\xE3\x81\x82\xE3\x82\xA4\xE3\x81\x86\xEF\xBD\xB4\xE3\x82\xAA",
       "\xE3\x81\x82\xE3\x81\x84\xE3\x81\x86\xE3\x81\x88\xE3\x81\x8A");
+
+  // whitespace -> string which should be placed at last
+  EXPECT_EQ_UTF8_UTF8("    \t", "\xF0\x9F\xBF\xBD");
 }
 
 int main() {