diff --git a/google/cloud/bigtable/data/_cross_sync/_decorators.py b/google/cloud/bigtable/data/_cross_sync/_decorators.py
index 4e79331dd..2f4c8374f 100644
--- a/google/cloud/bigtable/data/_cross_sync/_decorators.py
+++ b/google/cloud/bigtable/data/_cross_sync/_decorators.py
@@ -201,7 +201,7 @@ def __init__(
         sync_name: str | None = None,
         *,
         replace_symbols: dict[str, str] | None = None,
-        docstring_format_vars: dict[str, tuple[str, str]] | None = None,
+        docstring_format_vars: dict[str, tuple[str | None, str | None]] | None = None,
         rm_aio: bool = False,
         add_mapping_for_name: str | None = None,
     ):
@@ -209,10 +209,10 @@ def __init__(
         self.replace_symbols = replace_symbols
         docstring_format_vars = docstring_format_vars or {}
         self.async_docstring_format_vars = {
-            k: v[0] for k, v in docstring_format_vars.items()
+            k: v[0] or "" for k, v in docstring_format_vars.items()
         }
         self.sync_docstring_format_vars = {
-            k: v[1] for k, v in docstring_format_vars.items()
+            k: v[1] or "" for k, v in docstring_format_vars.items()
         }
         self.rm_aio = rm_aio
         self.add_mapping_for_name = add_mapping_for_name
diff --git a/tests/unit/data/_cross_sync/test_cross_sync_decorators.py b/tests/unit/data/_cross_sync/test_cross_sync_decorators.py
index fb35a5834..1f5bd4b0e 100644
--- a/tests/unit/data/_cross_sync/test_cross_sync_decorators.py
+++ b/tests/unit/data/_cross_sync/test_cross_sync_decorators.py
@@ -108,6 +108,10 @@ def test_class_decorator_adds_mapping(self):
             ["{A}", {"A": (1, 2)}, "1"],
             ["{A} {B}", {"A": (1, 2), "B": (3, 4)}, "1 3"],
             ["hello {world_var}", {"world_var": ("world", "moon")}, "hello world"],
+            ["{empty}", {"empty": ("", "")}, ""],
+            ["{empty}", {"empty": (None, None)}, ""],
+            ["maybe{empty}", {"empty": (None, "yes")}, "maybe"],
+            ["maybe{empty}", {"empty": (" no", None)}, "maybe no"]
         ],
     )
     def test_class_decorator_docstring_update(self, docstring, format_vars, expected):
@@ -123,8 +127,8 @@ class Class:
         assert Class.__doc__ == expected
         # check internal state
         instance = self._get_class()(sync_name="s", docstring_format_vars=format_vars)
-        async_replacements = {k: v[0] for k, v in format_vars.items()}
-        sync_replacements = {k: v[1] for k, v in format_vars.items()}
+        async_replacements = {k: v[0] or "" for k, v in format_vars.items()}
+        sync_replacements = {k: v[1] or "" for k, v in format_vars.items()}
         assert instance.async_docstring_format_vars == async_replacements
         assert instance.sync_docstring_format_vars == sync_replacements
 
@@ -299,6 +303,10 @@ def test_async_decorator_no_docstring(self):
             ["{A}", {"A": (1, 2)}, "1"],
             ["{A} {B}", {"A": (1, 2), "B": (3, 4)}, "1 3"],
             ["hello {world_var}", {"world_var": ("world", "moon")}, "hello world"],
+            ["{empty}", {"empty": ("", "")}, ""],
+            ["{empty}", {"empty": (None, None)}, ""],
+            ["maybe{empty}", {"empty": (None, "yes")}, "maybe"],
+            ["maybe{empty}", {"empty": (" no", None)}, "maybe no"]
         ],
     )
     def test_async_decorator_docstring_update(self, docstring, format_vars, expected):
@@ -314,8 +322,8 @@ class Class:
         assert Class.__doc__ == expected
         # check internal state
         instance = self._get_class()(docstring_format_vars=format_vars)
-        async_replacements = {k: v[0] for k, v in format_vars.items()}
-        sync_replacements = {k: v[1] for k, v in format_vars.items()}
+        async_replacements = {k: v[0] or "" for k, v in format_vars.items()}
+        sync_replacements = {k: v[1] or "" for k, v in format_vars.items()}
         assert instance.async_docstring_format_vars == async_replacements
         assert instance.sync_docstring_format_vars == sync_replacements