diff --git a/src/isdb/Caliber.cpp b/src/isdb/Caliber.cpp
index 72d0d2dd8907275a93b29d8d295d6526f4e91663..5076e9d3e8e631ccf52fda93c1c32365e041b12a 100644
--- a/src/isdb/Caliber.cpp
+++ b/src/isdb/Caliber.cpp
@@ -33,6 +33,7 @@ namespace isdb {
 //+PLUMEDOC ISDB_BIAS CALIBER
 /*
 Add a time-dependent, harmonic restraint on one or more variables.
+
 This allows implementing a maximum caliber restraint on one or more experimental time series by replica-averaged restrained simulations.
 See \cite Capelli:2018jt .