diff --git a/Exec/Make.Castro b/Exec/Make.Castro
index cfd7e187a9..79e747b5c8 100644
--- a/Exec/Make.Castro
+++ b/Exec/Make.Castro
@@ -270,6 +270,10 @@ ifeq ($(USE_ROTATION), TRUE)
   DEFINES += -DROTATION
 endif
 
+ifeq ($(USE_SPECIES_SOURCES), TRUE)
+  DEFINES += -DCONS_SPECIES_HAVE_SOURCES
+endif
+
 ifeq ($(USE_PARTICLES), TRUE)
   Bdirs += Source/particles
 endif
diff --git a/Source/driver/_variables b/Source/driver/_variables
index 36d05dfc06..b6408c82a8 100644
--- a/Source/driver/_variables
+++ b/Source/driver/_variables
@@ -16,9 +16,9 @@
    energy-density         UEDEN     NSRC                                  1                 None
    internal-energy        UEINT     NSRC                                  1                 None
    temperature            UTEMP     NSRC                                  1                 None
-   advected               UFA       None                                  NumAdv            None
-   species                UFS       None                                  NumSpec           None
-   auxiliary              UFX       None                                  NumAux            None
+   advected               UFA       [(NSRC, CONS_SPECIES_HAVE_SOURCES)]   NumAdv            None
+   species                UFS       [(NSRC, CONS_SPECIES_HAVE_SOURCES)]   NumSpec           None
+   auxiliary              UFX       [(NSRC, CONS_SPECIES_HAVE_SOURCES)]   NumAux            None
    shock                  USHK      None                                  1                 SHOCK_VAR
    mu_p                   UMUP      None                                  1                 NSE_NET
    mu_n                   UMUN      None                                  1                 NSE_NET