diff --git a/unit_test/burn_cell_primordial_chem/GNUmakefile b/unit_test/burn_cell_primordial_chem/GNUmakefile
index 8e288cca49..ba0024acf6 100644
--- a/unit_test/burn_cell_primordial_chem/GNUmakefile
+++ b/unit_test/burn_cell_primordial_chem/GNUmakefile
@@ -19,12 +19,6 @@ USE_MICROPHYSICS_DEBUG = TRUE
 
 EBASE = main
 
-USE_CXX_REACTIONS ?= TRUE
-
-ifeq ($(USE_CXX_REACTIONS),TRUE)
-  DEFINES += -DCXX_REACTIONS
-endif
-
 # define the location of the Microphysics top directory
 MICROPHYSICS_HOME  := ../..
 
diff --git a/unit_test/test_ase/GNUmakefile b/unit_test/test_ase/GNUmakefile
index 6946850e40..3ba0e1f7e6 100644
--- a/unit_test/test_ase/GNUmakefile
+++ b/unit_test/test_ase/GNUmakefile
@@ -16,12 +16,6 @@ USE_NSE_NET = TRUE
 EBASE = main
 
 
-USE_CXX_REACTIONS ?= TRUE
-
-ifeq ($(USE_CXX_REACTIONS),TRUE)
-  DEFINES += -DCXX_REACTIONS
-endif
-
 # define the location of the Microphysics top directory
 MICROPHYSICS_HOME  := ../..