diff --git a/CMakeLists.txt b/CMakeLists.txt
index eef1cb7fde..d8cdb320a7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -668,6 +668,9 @@ list( APPEND PROJECT_COMPILE_DEFINITIONS_OPTIONS
 # Only define if set, this is to use #ifdef/#ifndef preprocessors
 # in code since cmake cannot handle basically any others :(
 # https://gitlab.kitware.com/cmake/cmake/-/issues/17398
+if ( ${USE_DOUBLE} )
+  list( APPEND PROJECT_COMPILE_DEFINITIONS_OPTIONS DOUBLE_PRECISION )
+endif()
 if ( ${ENABLE_CHEM} )
   list( APPEND PROJECT_COMPILE_DEFINITIONS_OPTIONS WRF_CHEM=1 )
   if ( ${ENABLE_KPP} )
diff --git a/phys/module_mp_ntu.F b/phys/module_mp_ntu.F
index 001bd60c97..5629d63415 100644
--- a/phys/module_mp_ntu.F
+++ b/phys/module_mp_ntu.F
@@ -665,8 +665,6 @@ REAL FUNCTION GAMLN(XX)                                           ! Referred to
       GAMLN = TMP+LOG(stp*ser/X)
 #else
       GAMLN = SNGL(TMP+LOG(stp*ser/X))
-#else
-!      This is a temporary hack assuming double precision is 8 bytes.
 #endif
 
       END FUNCTION GAMLN