diff --git a/src/fetchcode/package_versions.py b/src/fetchcode/package_versions.py
index 5fa8116..da1096b 100644
--- a/src/fetchcode/package_versions.py
+++ b/src/fetchcode/package_versions.py
@@ -136,6 +136,9 @@ def get_cargo_versions_from_purl(purl):
     url = f"https://crates.io/api/v1/crates/{purl.name}"
     response = get_response(url=url, content_type="json", headers={"User-Agent": "pm_bot"})
 
+    if not response:
+        return
+    
     for version_info in response.get("versions"):
         yield PackageVersion(
             value=version_info["num"],
diff --git a/tests/test_package_versions.py b/tests/test_package_versions.py
index a73cc53..cc19ca7 100644
--- a/tests/test_package_versions.py
+++ b/tests/test_package_versions.py
@@ -79,6 +79,16 @@ def test_get_cargo_versions_from_purl(mock_get_response):
     check_results_against_json(result, expected_file)
 
 
+@mock.patch("fetchcode.package_versions.get_response")
+def test_get_cargo_versions_from_purl_no_response(mock_get_response):
+    mock_get_response.return_value = None
+    purl = "pkg:cargo/yprox"
+
+    result = list(versions(purl))
+
+    assert result == []
+
+
 @mock.patch("fetchcode.package_versions.get_response")
 def test_get_gem_versions_from_purl(mock_get_response):
     side_effect = [get_json_data(data_location / "gem_mock_data.json")]