diff --git a/doc/set.html b/doc/set.html
index 2d857ae54e..1c439ad155 100644
--- a/doc/set.html
+++ b/doc/set.html
@@ -43,7 +43,7 @@
   <I>quat/random</I> value = seed
     seed = random # seed (positive integer) for quaternion orientations
   <I>diameter</I> value = particle diameter (distance units)
-  <I>density</I> value = particle mass (mass/distance^3 units)
+  <I>density</I> value = particle density (mass/distance^3 units)
   <I>volume</I> value = particle volume (distance^3 units)
   <I>bond</I> value = bond type for all bonds between selected atoms
   <I>angle</I> value = angle type for all angles between selected atoms
diff --git a/doc/set.txt b/doc/set.txt
index 82edc5c17d..9ecc601dca 100644
--- a/doc/set.txt
+++ b/doc/set.txt
@@ -39,7 +39,7 @@ keyword = {type} or {type/fraction} or {mol} or \
   {quat/random} value = seed
     seed = random # seed (positive integer) for quaternion orientations
   {diameter} value = particle diameter (distance units)
-  {density} value = particle mass (mass/distance^3 units)
+  {density} value = particle density (mass/distance^3 units)
   {volume} value = particle volume (distance^3 units)
   {bond} value = bond type for all bonds between selected atoms
   {angle} value = angle type for all angles between selected atoms