diff --git a/gammapy/datasets/evaluator.py b/gammapy/datasets/evaluator.py
index 160ad4c43..c274ed418 100644
--- a/gammapy/datasets/evaluator.py
+++ b/gammapy/datasets/evaluator.py
@@ -384,6 +384,9 @@ class MapEvaluator:
         npred_reco : `~gammapy.maps.Map`
             Predicted counts in reconstructed energy bins.
         """
+        # No energy dispersion -> return unchanged
+        if self.edisp is None:
+            return npred
         if self.model.apply_irf["edisp"]:
             return apply_edisp(npred, self.edisp)
         else: