diff --git a/test/sv_find_first_not_of_test.cpp b/test/sv_find_first_not_of_test.cpp
index 2998e03..a32a6e1 100644
--- a/test/sv_find_first_not_of_test.cpp
+++ b/test/sv_find_first_not_of_test.cpp
@@ -524,6 +524,41 @@ int main()
         }
     }
 
+    {
+        wchar_t str[ 256 ];
+
+        for( int i = 0; i < 256; ++i )
+        {
+            str[ i ] = static_cast< wchar_t >( 0x100 + i );
+        }
+
+        boost::core::wstring_view sv( str, 256 );
+
+        BOOST_TEST_EQ( sv.find_first_not_of( sv ), npos );
+
+        std::wstring str2( sv.data(), sv.size() );
+
+        for( int i = 0; i < 256; ++i )
+        {
+            std::wstring str3( str2 );
+
+            str3[ i ] = ~str3[ i ];
+
+            BOOST_TEST_EQ( sv.find_first_not_of( str3 ), i );
+        }
+
+        std::reverse( str, str + 256 );
+
+        for( int i = 0; i < 256; ++i )
+        {
+            std::wstring str3( str2 );
+
+            str3[ i ] = ~str3[ i ];
+
+            BOOST_TEST_EQ( sv.find_first_not_of( str3 ), 255 - i );
+        }
+    }
+
 #if defined(__cpp_char8_t) && __cpp_char8_t >= 201811L
 
     {
diff --git a/test/sv_find_first_of_test.cpp b/test/sv_find_first_of_test.cpp
index 728d4f6..f5704c0 100644
--- a/test/sv_find_first_of_test.cpp
+++ b/test/sv_find_first_of_test.cpp
@@ -446,6 +446,31 @@ int main()
         }
     }
 
+    {
+        wchar_t str[ 256 ];
+
+        for( int i = 0; i < 256; ++i )
+        {
+            str[ i ] = static_cast< wchar_t >( 0x100 + i );
+        }
+
+        boost::core::wstring_view sv( str, 256 );
+
+        for( int i = 0; i < 256; ++i )
+        {
+            std::wstring needle( 12, static_cast< wchar_t >( 0x100 + i ) );
+            BOOST_TEST_EQ( sv.find_first_of( needle ), i );
+        }
+
+        std::reverse( str, str + 256 );
+
+        for( int i = 0; i < 256; ++i )
+        {
+            std::wstring needle( 12, static_cast< wchar_t >( 0x100 + i ) );
+            BOOST_TEST_EQ( sv.find_first_of( needle ), 255 - i );
+        }
+    }
+
 #if defined(__cpp_char8_t) && __cpp_char8_t >= 201811L
 
     {
diff --git a/test/sv_find_last_not_of_test.cpp b/test/sv_find_last_not_of_test.cpp
index 348eb29..96a71cd 100644
--- a/test/sv_find_last_not_of_test.cpp
+++ b/test/sv_find_last_not_of_test.cpp
@@ -524,6 +524,41 @@ int main()
         }
     }
 
+    {
+        wchar_t str[ 256 ];
+
+        for( int i = 0; i < 256; ++i )
+        {
+            str[ i ] = static_cast< wchar_t >( 0x100 + i );
+        }
+
+        boost::core::wstring_view sv( str, 256 );
+
+        BOOST_TEST_EQ( sv.find_first_not_of( sv ), npos );
+
+        std::wstring str2( sv.data(), sv.size() );
+
+        for( int i = 0; i < 256; ++i )
+        {
+            std::wstring str3( str2 );
+
+            str3[ i ] = ~str3[ i ];
+
+            BOOST_TEST_EQ( sv.find_first_not_of( str3 ), i );
+        }
+
+        std::reverse( str, str + 256 );
+
+        for( int i = 0; i < 256; ++i )
+        {
+            std::wstring str3( str2 );
+
+            str3[ i ] = ~str3[ i ];
+
+            BOOST_TEST_EQ( sv.find_first_not_of( str3 ), 255 - i );
+        }
+    }
+
 #if defined(__cpp_char8_t) && __cpp_char8_t >= 201811L
 
     {
diff --git a/test/sv_find_last_of_test.cpp b/test/sv_find_last_of_test.cpp
index 2008ab9..5cc0624 100644
--- a/test/sv_find_last_of_test.cpp
+++ b/test/sv_find_last_of_test.cpp
@@ -464,6 +464,31 @@ int main()
         }
     }
 
+    {
+        wchar_t str[ 256 ];
+
+        for( int i = 0; i < 256; ++i )
+        {
+            str[ i ] = static_cast< wchar_t >( 0x100 + i );
+        }
+
+        boost::core::wstring_view sv( str, 256 );
+
+        for( int i = 0; i < 256; ++i )
+        {
+            std::wstring needle( 12, static_cast< wchar_t >( 0x100 + i ) );
+            BOOST_TEST_EQ( sv.find_first_of( needle ), i );
+        }
+
+        std::reverse( str, str + 256 );
+
+        for( int i = 0; i < 256; ++i )
+        {
+            std::wstring needle( 12, static_cast< wchar_t >( 0x100 + i ) );
+            BOOST_TEST_EQ( sv.find_first_of( needle ), 255 - i );
+        }
+    }
+
 #if defined(__cpp_char8_t) && __cpp_char8_t >= 201811L
 
     {