diff --git a/ollama/_types.py b/ollama/_types.py
index 293bfa8..589c7aa 100644
--- a/ollama/_types.py
+++ b/ollama/_types.py
@@ -166,9 +166,14 @@ class Image(BaseModel):
       return b64encode(self.value.read_bytes() if isinstance(self.value, Path) else self.value).decode()
 
     if isinstance(self.value, str):
-      if Path(self.value).exists():
-        return b64encode(Path(self.value).read_bytes()).decode()
+      try:
+        if Path(self.value).exists():
+          return b64encode(Path(self.value).read_bytes()).decode()
+      except Exception:
+        # Long base64 string can't be wrapped in Path, so try to treat as base64 string
+        pass
 
+      # String might be a file path, but might not exist
       if self.value.split('.')[-1] in ('png', 'jpg', 'jpeg', 'webp'):
         raise ValueError(f'File {self.value} does not exist')
 
diff --git a/tests/test_type_serialization.py b/tests/test_type_serialization.py
index e3e8268..8200ce3 100644
--- a/tests/test_type_serialization.py
+++ b/tests/test_type_serialization.py
@@ -19,6 +19,12 @@ def test_image_serialization_base64_string():
   assert img.model_dump() == b64_str  # Should return as-is if valid base64
 
 
+def test_image_serialization_long_base64_string():
+  b64_str = 'dGVzdCBiYXNlNjQgc3RyaW5n' * 1000
+  img = Image(value=b64_str)
+  assert img.model_dump() == b64_str  # Should return as-is if valid base64
+
+
 def test_image_serialization_plain_string():
   img = Image(value='not a path or base64')
   assert img.model_dump() == 'not a path or base64'  # Should return as-is