diff --git a/book/src/list-units.md b/book/src/list-units.md
index 49d1718c..92817689 100644
--- a/book/src/list-units.md
+++ b/book/src/list-units.md
@@ -124,6 +124,7 @@ and — where sensible — units allow for [binary prefixes](https://en.wikipedi
 | [Sidereal day](https://en.wikipedia.org/wiki/Sidereal_time#Sidereal_day) | `sidereal_day`, `sidereal_days` |
 | [Siemens](https://en.wikipedia.org/wiki/Siemens_(unit)) | `siemens`, `S` |
 | [Sievert](https://en.wikipedia.org/wiki/Sievert) | `sieverts`, `sievert`, `Sv` |
+| [Smoot](https://en.wikipedia.org/wiki/Smoot) | `smoots`, `smoot` |
 | [Steradian](https://en.wikipedia.org/wiki/Steradian) | `steradian`, `steradians`, `sr` |
 | [Stokes](https://en.wikipedia.org/wiki/Viscosity#Units) | `stokes`, `St` |
 | [Stoney length](https://en.wikipedia.org/wiki/Stoney_units) | `stoney_length` |
diff --git a/numbat/modules/prelude.nbt b/numbat/modules/prelude.nbt
index 7d6a2b09..4ad93cb6 100644
--- a/numbat/modules/prelude.nbt
+++ b/numbat/modules/prelude.nbt
@@ -18,6 +18,7 @@ use units::cgs
 use units::planck
 use units::fff
 use units::misc
+use units::humorous
 use units::partsperx
 
 use units::currency
diff --git a/numbat/modules/units/humorous.nbt b/numbat/modules/units/humorous.nbt
new file mode 100644
index 00000000..429383cf
--- /dev/null
+++ b/numbat/modules/units/humorous.nbt
@@ -0,0 +1,6 @@
+use units::si
+use units::imperial
+
+# https://en.wikipedia.org/wiki/Smoot
+unit smoot: Length = 5 feet + 7 inch
+