diff --git a/R/simulate-methods.R b/R/simulate-methods.R
index e0290e4..6c44d7b 100644
--- a/R/simulate-methods.R
+++ b/R/simulate-methods.R
@@ -95,6 +95,8 @@ setMethod("simulate", signature(object = "a4aFitSA"),
 			attr(out@index[[i]], "range") <- attr(object@index[[i]], "range")
 		}
     }
+
+    units(out) <- units(object)
     out
 })