diff --git a/Common/read_snapshot.f90 b/Common/read_snapshot.f90
index 48c50a69b440b6327bdc4961eb67e74ea707c69c..295d3c9121a1104af0a15b2ddf4279d278fc63f6 100644
--- a/Common/read_snapshot.f90
+++ b/Common/read_snapshot.f90
@@ -55,7 +55,15 @@ contains
        call read_eddy(e, d, i, hshp, ishape)
 
        ! Check that all the eddies have the same date index:
-       call assert(d - d_init == k, "read_snapshot: date index")
+       if (d - d_init /= k) then
+          print *, "read_snapshot: bad date index"
+          print *, "d = ", d
+          print *, "d_init = ", d_init
+          print *, "k = ", k
+          print *, "ishape = ", ishape
+          print *, "i = ", i
+          stop 1
+       end if
 
        s%list(i) = e
     end do