diff --git a/src/aspire/nufft/finufft.py b/src/aspire/nufft/finufft.py
index 082fd31f77..9c41fdd3de 100644
--- a/src/aspire/nufft/finufft.py
+++ b/src/aspire/nufft/finufft.py
@@ -103,6 +103,9 @@ def transform(self, signal):
             f"Signal frame to be transformed must have shape {self.sz}",
         )
 
+        # FINUFFT was designed for a complex input array
+        signal = np.array(signal, copy=False, dtype=self.complex_dtype, order="C")
+
         result = self._transform_plan.execute(signal)
 
         return result
@@ -135,6 +138,9 @@ def adjoint(self, signal):
             if self.ntransforms == 1:
                 signal = signal.reshape(self.num_pts)
 
+        # FINUFFT was designed for a complex input array
+        signal = np.array(signal, copy=False, dtype=self.complex_dtype, order="C")
+
         result = self._adjoint_plan.execute(signal)
 
         return result