diff --git a/pypocketfft.cc b/pypocketfft.cc
index 5c74ef1ab0aaea4c5aeb32f53777c723e8bedc5a..e96a0da8fb6171ab93b8b19c72fa73cf9e30d44f 100644
--- a/pypocketfft.cc
+++ b/pypocketfft.cc
@@ -151,7 +151,7 @@ template<typename T> py::array irfftn_internal(const py::array &in,
     throw runtime_error("bad lastsize");
   dims_out[axis] = lastsize;
   py::array res = py::array_t<T>(dims_out);
-  c2r(dims_in, lastsize, copy_strides(in), copy_strides(res), axes,
+  c2r(dims_out, copy_strides(in), copy_strides(res), axes,
     reinterpret_cast<const complex<T> *>(in.data()),
     reinterpret_cast<T *>(res.mutable_data()), T(fct));
   return res;