diff --git a/app/scodoc/TrivialFormulator.py b/app/scodoc/TrivialFormulator.py
index d14d5e6a0..e8871b123 100644
--- a/app/scodoc/TrivialFormulator.py
+++ b/app/scodoc/TrivialFormulator.py
@@ -206,10 +206,11 @@ class TF(object):
                 if self.values[field] == None:
                     self.values[field] = ""
 
-            # convert numbers
-            if type(self.values[field]) == type(1) or type(self.values[field]) == type(
-                1.0
-            ):
+            # convert numbers, except ids
+            if field.endswith("id") and self.values[field]:
+                # enforce integer ids:
+                self.values[field] = int(self.values[field])
+            elif isinstance(self.values[field], (int, float)):
                 self.values[field] = str(self.values[field])
         #
         if "tf-checked" not in self.values: