diff --git a/doc/pair_modify.html b/doc/pair_modify.html
index a5aa4a2025..91dc591f5b 100644
--- a/doc/pair_modify.html
+++ b/doc/pair_modify.html
@@ -162,6 +162,14 @@ checking the rdf. The rdf is not exactly unity beyond the cutoff for
each pair of interaction types, so the tail correction is necessarily
an approximation.
+The tail corrections are computed at the beginning of each simulation
+run. If the number of atoms changes during the run, e.g. due to atoms
+leaving the simulation domain, or use of the fix gcmc
+command, then the corrections are not updates to relect the changed
+atom count. If this is a large effect in your simulation, you should
+break the long run into several short runs, so that the correction
+factors are re-computed multiple times.
+
Thermophysical properties obtained from calculations with this option
enabled will not be thermodynamically consistent with the truncated
force-field that was used. In other words, atoms do not feel any LJ
diff --git a/doc/pair_modify.txt b/doc/pair_modify.txt
index af00c3a593..b2844fc938 100644
--- a/doc/pair_modify.txt
+++ b/doc/pair_modify.txt
@@ -156,6 +156,14 @@ checking the rdf. The rdf is not exactly unity beyond the cutoff for
each pair of interaction types, so the tail correction is necessarily
an approximation. :l
+The tail corrections are computed at the beginning of each simulation
+run. If the number of atoms changes during the run, e.g. due to atoms
+leaving the simulation domain, or use of the "fix gcmc"_fix_gcmc.html
+command, then the corrections are not updates to relect the changed
+atom count. If this is a large effect in your simulation, you should
+break the long run into several short runs, so that the correction
+factors are re-computed multiple times.
+
Thermophysical properties obtained from calculations with this option
enabled will not be thermodynamically consistent with the truncated
force-field that was used. In other words, atoms do not feel any LJ