diff --git a/Source/func.f90 b/Source/func.f90
index bfc329f9c0..92f806cd19 100644
--- a/Source/func.f90
+++ b/Source/func.f90
@@ -2813,20 +2813,21 @@ END SUBROUTINE GET_Y_SURF
 
 SUBROUTINE GET_TMP_REF(N_MATL,NR)
 INTEGER, INTENT(IN) :: N_MATL,NR
-REAL(EB) :: HEATING_RATE,DT=0.01_EB,DTDT,RR_MAX,REACTION_RATE,TMP,RHO_S
+REAL(EB) :: HEATING_RATE,DTMP=0.01_EB,DT,DTMPDT,RR_MAX,REACTION_RATE,TMP,RHO_S
 TYPE(MATERIAL_TYPE), POINTER :: ML
 
 ML=> MATERIAL(N_MATL)
 
 IF (ML%RATE_REF(NR) > 0._EB) THEN
-   HEATING_RATE = ML%RATE_REF(NR)
+   HEATING_RATE = ML%HEATING_RATE(NR)
 ELSE
    HEATING_RATE = TGA_HEATING_RATE
 ENDIF
 
 TMP = 0._EB
 ML%TMP_REF(NR) = 0._EB
-DTDT = HEATING_RATE/60._EB
+DTMPDT = HEATING_RATE/60._EB
+DT = DTMP/DTMPDT
 RHO_S = ML%RHO_S
 IF (ABS(ML%E(NR)) < TWENTY_EPSILON_EB) THEN
    RR_MAX = ML%A(NR)*RHO_S**ML%N_S(NR)
@@ -2835,7 +2836,7 @@ SUBROUTINE GET_TMP_REF(N_MATL,NR)
 ENDIF
 
 DO WHILE (INT(TMP)<I_MAX_TEMP)
-   TMP = TMP + DTDT * DT
+   TMP = TMP + DTMP
    REACTION_RATE = ML%A(NR)*RHO_S**ML%N_S(NR)*EXP(-ML%E(NR)/(R0*TMP))*TMP**ML%N_T(NR)*ML%X_O2_PYRO**ML%N_O2(NR)
    IF (REACTION_RATE > RR_MAX) THEN
       ML%TMP_REF(NR) = TMP