diff --git a/misc/CMake/BRLCAD_ExternalDeps.cmake b/misc/CMake/BRLCAD_ExternalDeps.cmake
--- a/misc/CMake/BRLCAD_ExternalDeps.cmake
+++ b/misc/CMake/BRLCAD_ExternalDeps.cmake
@@ -1069,6 +1069,9 @@ endfunction(brlcad_bext_process)
 # Not all packages will define all of these, but it shouldn't matter -
 # an unset of an unused variable shouldn't be harmful
 function(find_package_reset pname trigger_var)
+  if(NOT ${trigger_var})
+    return()
+  endif(NOT ${trigger_var})
   unset(${pname}_DIR CACHE)
   unset(${pname}_CONFIG CACHE)
   unset(${pname}_DEFINITIONS CACHE)