diff --git a/src/ragas/testset/synthesizers/prompts.py b/src/ragas/testset/synthesizers/prompts.py
index b00813613..1ace435d9 100644
--- a/src/ragas/testset/synthesizers/prompts.py
+++ b/src/ragas/testset/synthesizers/prompts.py
@@ -7,7 +7,7 @@
 
 
 class ThemesPersonasInput(BaseModel):
-    themes: t.List[str]
+    themes: t.List[t.Union[str, t.Tuple[str, str]]]
     personas: t.List[Persona]