diff --git a/backend/src/hatchling/builders/hooks/custom.py b/backend/src/hatchling/builders/hooks/custom.py
index a561f993f..7d3fbbd30 100644
--- a/backend/src/hatchling/builders/hooks/custom.py
+++ b/backend/src/hatchling/builders/hooks/custom.py
@@ -29,7 +29,8 @@ def __new__(  # type: ignore[misc]
 
         path = os.path.normpath(os.path.join(root, build_script))
         if not os.path.isfile(path):
-            message = f"Build script does not exist: {build_script}"
+            relative_to_root = " (relative to project root)" if not os.path.isabs(build_script) else ""
+            message = f"Build script does not exist: {build_script}{relative_to_root}"
             raise OSError(message)
 
         hook_class = load_plugin_from_script(path, build_script, BuildHookInterface, "build_hook")
diff --git a/tests/backend/builders/hooks/test_custom.py b/tests/backend/builders/hooks/test_custom.py
index 48c1b1616..c068edbc5 100644
--- a/tests/backend/builders/hooks/test_custom.py
+++ b/tests/backend/builders/hooks/test_custom.py
@@ -22,8 +22,18 @@ def test_path_not_string(isolation):
 
 def test_nonexistent(isolation):
     config = {"path": "test.py"}
+    expected_message = "Build script does not exist: test.py (relative to project root)"
 
-    with pytest.raises(OSError, match="Build script does not exist: test.py"):
+    with pytest.raises(OSError, match=f"^{re.escape(expected_message)}$"):
+        CustomBuildHook(str(isolation), config, None, None, "", "")
+
+
+def test_nonexistent_absolute_path(isolation):
+    build_script = str(isolation / "test.py")
+    config = {"path": build_script}
+    expected_message = f"Build script does not exist: {build_script}"
+
+    with pytest.raises(OSError, match=f"^{re.escape(expected_message)}$"):
         CustomBuildHook(str(isolation), config, None, None, "", "")