diff --git a/tests/suites/test_suite_base64.data b/tests/suites/test_suite_base64.data
index 3a892f4..1f94c54 100644
--- a/tests/suites/test_suite_base64.data
+++ b/tests/suites/test_suite_base64.data
@@ -1,3 +1,33 @@
+mask_of_range empty (1..0)
+mask_of_range:1:0
+
+mask_of_range empty (255..0)
+mask_of_range:255:0
+
+mask_of_range empty (42..7)
+mask_of_range:42:7
+
+mask_of_range 0..0
+mask_of_range:0:0
+
+mask_of_range 42..42
+mask_of_range:42:42
+
+mask_of_range 255..255
+mask_of_range:255:255
+
+mask_of_range 0..255
+mask_of_range:0:255
+
+mask_of_range 'A'..'Z'
+mask_of_range:65:90
+
+enc_char (all digits)
+enc_chars:"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
+
+dec_value (all characters)
+dec_chars:"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
+
 Test case mbedtls_base64_encode #1 buffer just right
 mbedtls_base64_encode:"":"":0:0
 
diff --git a/tests/suites/test_suite_base64.function b/tests/suites/test_suite_base64.function
index be9b6e8..89d7995 100644
--- a/tests/suites/test_suite_base64.function
+++ b/tests/suites/test_suite_base64.function
@@ -8,6 +8,64 @@
  * END_DEPENDENCIES
  */
 
+/* BEGIN_CASE depends_on:MBEDTLS_TEST_HOOKS */
+void mask_of_range( int low_arg, int high_arg )
+{
+    unsigned char low = low_arg, high = high_arg;
+    unsigned c;
+    for( c = 0; c <= 0xff; c++ )
+    {
+        mbedtls_test_set_step( c );
+        TEST_CF_SECRET( &c, sizeof( c ) );
+        unsigned char m = mbedtls_base64_mask_of_range( low, high, c );
+        TEST_CF_PUBLIC( &c, sizeof( c ) );
+        if( low <= c && c <= high )
+            TEST_EQUAL( m, 0xff );
+        else
+            TEST_EQUAL( m, 0 );
+    }
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_TEST_HOOKS */
+void enc_chars( char *chars )
+{
+    for( unsigned value = 0; value < 64; value++ )
+    {
+        mbedtls_test_set_step( value );
+        TEST_CF_SECRET( &value, sizeof( value ) );
+        unsigned char digit = mbedtls_base64_enc_char( value );
+        TEST_CF_PUBLIC( &value, sizeof( value ) );
+        TEST_CF_PUBLIC( &digit, sizeof( digit ) );
+        TEST_EQUAL( digit, chars[value] );
+    }
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_TEST_HOOKS */
+void dec_chars( char *chars )
+{
+    char *p;
+    const size_t chars_len = strlen( chars );
+    signed char expected;
+
+    for( unsigned c = 0; c <= 0xff; c++ )
+    {
+        mbedtls_test_set_step( c );
+        p = memchr( chars, c, chars_len );
+        if( p == NULL )
+            expected = -1;
+        else
+            expected = p - chars;
+        TEST_CF_SECRET( &c, sizeof( c ) );
+        signed char actual = mbedtls_base64_dec_value( c );
+        TEST_CF_PUBLIC( &c, sizeof( c ) );
+        TEST_CF_PUBLIC( &actual, sizeof( actual ) );
+        TEST_EQUAL( actual, expected );
+    }
+}
+/* END_CASE */
+
 /* BEGIN_CASE */
 void mbedtls_base64_encode( char * src_string, char * dst_string,
                             int dst_buf_size, int result )