diff --git a/doc/manual/source/the-model-file.rst b/doc/manual/source/the-model-file.rst
index 82955ef4ab8276343d538f92e834e15c1bb0e3db..b45fce6ad8f8082c6d96a3e18826cd1b882cf5cc 100644
--- a/doc/manual/source/the-model-file.rst
+++ b/doc/manual/source/the-model-file.rst
@@ -7052,9 +7052,9 @@ observed variables.
 
     .. option:: prior_trunc = DOUBLE
 
-       Probability of extreme values of the prior density that is
+       Probability of extreme values of the prior density in each tail that is
        ignored when computing bounds for the parameters. Default:
-       ``1e-32``.
+       ``1e-10``.
 
     .. option:: huge_number = DOUBLE