diff --git a/qutip/core/qobj.py b/qutip/core/qobj.py
index fb33df6071..2f5aa0a345 100644
--- a/qutip/core/qobj.py
+++ b/qutip/core/qobj.py
@@ -828,7 +828,7 @@ def expm(self, dtype) -> Qobj:
                         dims=self._dims,
                         isherm=self._isherm,
                         copy=False)
-        return Qobj(_data.expm(self._data, dtype=dtype),
+        return Qobj(_data.expm(self._data, dtype=self.dtype),
                     dims=self._dims,
                     isherm=self._isherm,
                     copy=False)