diff --git a/python/_cosmotool.pyx b/python/_cosmotool.pyx
index 3e58ffb..366238f 100644
--- a/python/_cosmotool.pyx
+++ b/python/_cosmotool.pyx
@@ -538,9 +538,12 @@ def loadRamses(str basepath, int snapshot_id, int cpu_id, bool doublePrecision =
   if loadId:
      flags |= NEED_GADGET_ID
 
-  data = loadRamsesSimu(basepath, snapshot_id, cpu_id, doublePrecision, flags)
-  if data == <SimuData*>0:
-    return None
+  try:
+    data = loadRamsesSimu(basepath, snapshot_id, cpu_id, doublePrecision, flags)
+    if data == <SimuData*>0:
+      return None
+  except RuntimeError as e:
+    raise RuntimeError(e.message + ' (check the float precision in snapshot)')
 
   return PySimulationAdaptor(wrap_simudata(data, flags))