diff --git a/src/font16seg.py b/src/font16seg.py
index c863eb0..3969f84 100644
--- a/src/font16seg.py
+++ b/src/font16seg.py
@@ -362,3 +362,18 @@ def text(x, y, txt, *, color=None, unlit_color=None):
             x -= delta
         elif _rotate == 270:
             y -= delta
+
+def assign(code, flags):
+    """
+    Assign a glyph to a specific character code.
+
+    Parameters
+    ----------
+    code : int
+        Character code to assign the glyph.
+    flags : int
+        16-bit flags which segment is to be lit.
+    """
+    if flags < 0 or flags > 0b1111111111111111:
+        raise ValueError('flags must be in the range of 0-65535')
+    __CHARACTERS[code] = (__TYPE_16SEG, flags)
diff --git a/tests/test_font16seg.py b/tests/test_font16seg.py
index d2fc1be..5c829da 100644
--- a/tests/test_font16seg.py
+++ b/tests/test_font16seg.py
@@ -196,3 +196,62 @@ def test_textWidth_with_period(self):
     def test_textWidth_with_period_only(self):
         font16seg.attrib16seg(10, 8, lcd.WHITE, letter_spacing=1)
         self.assertEqual(font16seg.textWidth("."), 8)
+
+    def test_assign(self):
+        lcd.screensize = MagicMock(return_value=(136, 241))
+        lcd.triangle = MagicMock()
+        lcd.rect = MagicMock()
+
+        font16seg.attrib16seg(8, 2, lcd.WHITE, unlit_color=None)
+        font16seg.assign(ord("d"), 0b0000001111000111)
+        font16seg.text(0, 0, "d")
+        self.assertEqual(lcd.triangle.call_count, 14)
+        self.assertEqual(lcd.rect.call_count, 7)
+
+    def test_assign_min(self):
+        lcd.screensize = MagicMock(return_value=(136, 241))
+        lcd.triangle = MagicMock()
+        lcd.rect = MagicMock()
+
+        font16seg.attrib16seg(8, 2, lcd.WHITE, unlit_color=None)
+        font16seg.assign(ord("x"), 0)
+        font16seg.text(0, 0, "x")
+        lcd.triangle.assert_not_called()
+        lcd.rect.assert_not_called()
+
+    def test_assign_max(self):
+        lcd.screensize = MagicMock(return_value=(136, 241))
+        lcd.triangle = MagicMock()
+        lcd.rect = MagicMock()
+
+        font16seg.attrib16seg(8, 2, lcd.WHITE, unlit_color=None)
+        font16seg.assign(ord("x"), 0b1111111111111111)
+        font16seg.text(0, 0, "x")
+        self.assertEqual(lcd.triangle.call_count, 32)
+        self.assertEqual(lcd.rect.call_count, 12)
+
+    def test_assign_out_of_range(self):
+        with self.assertRaises(ValueError):
+            font16seg.assign(ord("x"), -1)
+
+        with self.assertRaises(ValueError):
+            font16seg.assign(ord("x"), 0b10000000000000000)
+
+    def test_assign_overwrite(self):
+        lcd.screensize = MagicMock(return_value=(136, 241))
+        lcd.triangle = MagicMock()
+        lcd.rect = MagicMock()
+
+        font16seg.attrib16seg(8, 2, lcd.WHITE, unlit_color=None)
+
+        font16seg.text(0, 0, "1")
+        self.assertEqual(lcd.triangle.call_count, 4)
+        self.assertEqual(lcd.rect.call_count, 2)
+
+        lcd.triangle.reset_mock()
+        lcd.rect.reset_mock()
+
+        font16seg.assign(ord("1"), 0b1000100000010011)
+        font16seg.text(0, 0, "1")
+        self.assertEqual(lcd.triangle.call_count, 10)
+        self.assertEqual(lcd.rect.call_count, 5)