diff --git a/oskar-spark/src/main/python/pyoskar/core.py b/oskar-spark/src/main/python/pyoskar/core.py
index c6e4eeb..09d12d3 100644
--- a/oskar-spark/src/main/python/pyoskar/core.py
+++ b/oskar-spark/src/main/python/pyoskar/core.py
@@ -335,9 +335,9 @@ def variantMetadata(self, df):
 
     def samples(self, df, studyId=None):
         if studyId is None:
-            return self._call_java("samples", df)
+            return self.python_utils.toPythonDict(self._call_java("samples", df))
         else:
-            return self._call_java("samples", df, studyId)
+            return self.python_utils.toPythonDict(self._call_java("samples", df, studyId))
 
     def pedigrees(self, df, studyId=None):
         if studyId is None: