diff --git a/src/neo4j/_async/bookmark_manager.py b/src/neo4j/_async/bookmark_manager.py
index b9a278c5..004e0847 100644
--- a/src/neo4j/_async/bookmark_manager.py
+++ b/src/neo4j/_async/bookmark_manager.py
@@ -51,10 +51,13 @@ def __init__(
         if not initial_bookmarks:
             self._bookmarks = set()
         else:
-            self._bookmarks = set(getattr(
-                initial_bookmarks, "raw_values",
-                t.cast(t.Iterable[str], initial_bookmarks)
-            ))
+            if not hasattr(initial_bookmarks, "raw_values"):
+                initial_bookmarks = Bookmarks.from_raw_values(
+                    t.cast(t.Iterable[str], initial_bookmarks)
+                )
+            self._bookmarks = set(
+                t.cast(Bookmarks, initial_bookmarks).raw_values
+            )
         self._lock = AsyncCooperativeLock()
 
     async def update_bookmarks(
diff --git a/src/neo4j/_sync/bookmark_manager.py b/src/neo4j/_sync/bookmark_manager.py
index b75b7493..c2cd522a 100644
--- a/src/neo4j/_sync/bookmark_manager.py
+++ b/src/neo4j/_sync/bookmark_manager.py
@@ -51,10 +51,13 @@ def __init__(
         if not initial_bookmarks:
             self._bookmarks = set()
         else:
-            self._bookmarks = set(getattr(
-                initial_bookmarks, "raw_values",
-                t.cast(t.Iterable[str], initial_bookmarks)
-            ))
+            if not hasattr(initial_bookmarks, "raw_values"):
+                initial_bookmarks = Bookmarks.from_raw_values(
+                    t.cast(t.Iterable[str], initial_bookmarks)
+                )
+            self._bookmarks = set(
+                t.cast(Bookmarks, initial_bookmarks).raw_values
+            )
         self._lock = CooperativeLock()
 
     def update_bookmarks(
diff --git a/src/neo4j/api.py b/src/neo4j/api.py
index 4306bb98..9af802cb 100644
--- a/src/neo4j/api.py
+++ b/src/neo4j/api.py
@@ -287,8 +287,12 @@ def from_raw_values(cls, values: t.Iterable[str]) -> Bookmarks:
         bookmarks.
 
         :param values: ASCII string values (raw bookmarks)
-        :type values: Iterable[str]
         """
+        if isinstance(values, str):
+            # Unfortunately, str itself is an iterable of str, iterating
+            # over characters. Type checkers will not catch this, so we help
+            # the user out.
+            values = values,
         obj = cls()
         bookmarks = []
         for value in values: