diff --git a/undocumented-keys.txt b/undocumented-keys.txt
index 1a6da2e9acbd298a4d6548747dd70c36e715f3f8..daaab1c3373863714f0ca72a2d5f8a79ba46bce0 100644
--- a/undocumented-keys.txt
+++ b/undocumented-keys.txt
@@ -18,7 +18,6 @@ diffusion.rtol
 diffusion.verbose_solver
 eb2.extend_domain_face
 fab.format
-fluid_name.thermal_conductivity
 hopper.center
 hopper.direction
 hopper.funnel_height