diff --git a/Tests/test_file_gbr.py b/Tests/test_file_gbr.py
index b8851d82b..d89ef0583 100644
--- a/Tests/test_file_gbr.py
+++ b/Tests/test_file_gbr.py
@@ -33,7 +33,7 @@ def test_multiple_load_operations() -> None:
         assert_image_equal_tofile(im, "Tests/images/gbr.png")
 
 
-def create_gbr_image(info: dict[str, int] = {}, magic_number=b"") -> BytesIO:
+def create_gbr_image(info: dict[str, int] = {}, magic_number: bytes = b"") -> BytesIO:
     return BytesIO(
         b"".join(
             _binary.o32be(i)
diff --git a/Tests/test_file_iptc.py b/Tests/test_file_iptc.py
index 5a8aaa3ef..0376b9997 100644
--- a/Tests/test_file_iptc.py
+++ b/Tests/test_file_iptc.py
@@ -12,7 +12,7 @@ TEST_FILE = "Tests/images/iptc.jpg"
 
 
 def create_iptc_image(info: dict[str, int] = {}) -> BytesIO:
-    def field(tag, value):
+    def field(tag: tuple[int, int], value: bytes) -> bytes:
         return bytes((0x1C,) + tag + (0, len(value))) + value
 
     data = field((3, 60), bytes((info.get("layers", 1), info.get("component", 0))))
diff --git a/Tests/test_imagetext.py b/Tests/test_imagetext.py
index 7db229897..46afea064 100644
--- a/Tests/test_imagetext.py
+++ b/Tests/test_imagetext.py
@@ -32,6 +32,10 @@ def test_get_length(font: ImageFont.FreeTypeFont) -> None:
     assert ImageText.Text("y", font).get_length() == 12
     assert ImageText.Text("a", font).get_length() == 12
 
+    text = ImageText.Text("\n", font)
+    with pytest.raises(ValueError, match="can't measure length of multiline text"):
+        text.get_length()
+
 
 def test_get_bbox(font: ImageFont.FreeTypeFont) -> None:
     assert ImageText.Text("A", font).get_bbox() == (0, 4, 12, 16)
@@ -45,6 +49,7 @@ def test_standard_embedded_color(layout_engine: ImageFont.Layout) -> None:
     font = ImageFont.truetype(FONT_PATH, 40, layout_engine=layout_engine)
     text = ImageText.Text("Hello World!", font)
     text.embed_color()
+    assert text.get_length() == 288
 
     im = Image.new("RGB", (300, 64), "white")
     draw = ImageDraw.Draw(im)
@@ -52,6 +57,12 @@ def test_standard_embedded_color(layout_engine: ImageFont.Layout) -> None:
 
     assert_image_similar_tofile(im, "Tests/images/standard_embedded.png", 3.1)
 
+    text = ImageText.Text("", mode="1")
+    with pytest.raises(
+        ValueError, match="Embedded color supported only in RGB and RGBA modes"
+    ):
+        text.embed_color()
+
 
 @skip_unless_feature("freetype2")
 def test_stroke() -> None:
diff --git a/src/PIL/ImageText.py b/src/PIL/ImageText.py
index c74570e69..e6ccd8243 100644
--- a/src/PIL/ImageText.py
+++ b/src/PIL/ImageText.py
@@ -88,7 +88,7 @@ class Text:
         else:
             return "L"
 
-    def get_length(self):
+    def get_length(self) -> float:
         """
         Returns length (in pixels with 1/64 precision) of text.
 
@@ -130,8 +130,11 @@ class Text:
 
         :return: Either width for horizontal text, or height for vertical text.
         """
-        split_character = "\n" if isinstance(self.text, str) else b"\n"
-        if split_character in self.text:
+        if isinstance(self.text, str):
+            multiline = "\n" in self.text
+        else:
+            multiline = b"\n" in self.text
+        if multiline:
             msg = "can't measure length of multiline text"
             raise ValueError(msg)
         return self.font.getlength(
@@ -313,6 +316,5 @@ class Text:
                     max(bbox[3], bbox_line[3]),
                 )
 
-        if bbox is None:
-            return xy[0], xy[1], xy[0], xy[1]
+        assert bbox is not None
         return bbox