diff --git a/orgroamtools/data.py b/orgroamtools/data.py
index 1aecc4a..5d3a31f 100644
--- a/orgroamtools/data.py
+++ b/orgroamtools/data.py
@@ -1182,7 +1182,7 @@ def get_latex_snippets(self, identifier: str) -> list[str]:
                 raise AttributeError(f"No node with identifier: {identifier}")
 
     @property
-    def src_block_index(self) -> dict[str, list[tuple[str, list[str]]]]:
+    def src_block_index(self) -> dict[str, list[tuple[str, str]]]:
         """Return index of source blocks of nodes
 
         Returns