diff --git a/src/docx/package.py b/src/docx/package.py
index 7ea47e6e1..9132c4339 100644
--- a/src/docx/package.py
+++ b/src/docx/package.py
@@ -88,6 +88,10 @@ def _get_by_sha1(self, sha1: str) -> ImagePart | None:
         """Return the image part in this collection having a SHA1 hash matching `sha1`,
         or |None| if not found."""
         for image_part in self._image_parts:
+            # ---skip parts loaded for an unsupported image type (e.g. SVG), which
+            # ---come through the image relationships as a plain Part and have no sha1
+            if not hasattr(image_part, "sha1"):
+                continue
             if image_part.sha1 == sha1:
                 return image_part
         return None
diff --git a/tests/test_package.py b/tests/test_package.py
index ac9839828..6eef18bf7 100644
--- a/tests/test_package.py
+++ b/tests/test_package.py
@@ -8,6 +8,7 @@
 
 from docx.image.image import Image
 from docx.opc.packuri import PackURI
+from docx.opc.part import Part
 from docx.package import ImageParts, Package
 from docx.parts.image import ImagePart
 
@@ -102,6 +103,18 @@ def but_it_adds_a_new_image_part_when_match_fails(
         _add_image_part_.assert_called_once_with(image_parts, image_)
         assert image_part is image_part_
 
+    def it_skips_parts_without_a_sha1_when_matching(self, request: FixtureRequest):
+        # ---an unsupported image type (e.g. SVG) is reached through the image
+        # ---relationships as a plain Part with no sha1, and must be skipped
+        # ---rather than raising AttributeError---
+        non_image_part = instance_mock(request, Part)
+        image_part = instance_mock(request, ImagePart, sha1="f005ba11")
+        image_parts = ImageParts()
+        image_parts.append(non_image_part)
+        image_parts.append(image_part)
+
+        assert image_parts._get_by_sha1("f005ba11") is image_part
+
     @pytest.mark.parametrize(
         ("existing_partname_numbers", "expected_partname_number"),
         [