diff --git a/code/ysolve.f90 b/code/ysolve.f90
index be1c76d..887a1e9 100644
--- a/code/ysolve.f90
+++ b/code/ysolve.f90
@@ -159,14 +159,14 @@
       INTEGER :: i,j,k,nd
       REAL, DIMENSION(2,nx) :: ux,dux,d2ux
       REAL, DIMENSION(10,nx) :: sav
-        
+
       sav=0.
 
 !      refwr=pre*1.*exp(-ac/(1.+bc*c_cut))
 !      minf=exp((c_ref-c_cut)*prof_wr)
       refwr=pre*1.*exp(-ac/(1.+bc*c_ref))   
-     
-               
+
+
       WRITE(500,*) 'VARIABLES = "X","Yr","C","U","Wrate","|DEL(Y)|","Sdr"'
       WRITE(500,*) ' "Sdd","Sd","(1/C)/(dC/dx)","DIV(rho*Dmu*Gra(C))"'
 
@@ -175,7 +175,7 @@
        ux(2,i)=y1(i,2)                               ! T
        IF (ux(1,i).gt.1.) ux(1,i)=1.                                  
       ENDDO
-          
+
       nd=2
       CALL dfnonp(nx,hx,ux(:,:),dux(:,:),nd,1)
       CALL d2fnonp(nx,hx,ux(:,:),d2ux(:,:),nd,1)
@@ -252,25 +252,41 @@
       REAL :: ya,yx
       INTEGER :: i
       REAL, DIMENSION(1,nx) :: ux, dux
-      
+
+      if ( reaction_type == "onestep" ) then
+
       DO i=1,nx
        yr=y1(i,1)
+       theta=y1(i,2)
 
+       ux(1,i)=theta
+
+        wrate=rate_1step(yr, theta)
+
+       S_L=S_L+wrate*hx
+      ENDDO
+
+      else if ( reaction_type == "twostep" ) then
+
+      DO i=1,nx
        ya=y1(i,1)
        yx=y1(i,2)
        theta=y1(i,3)
 
        ux(1,i)=theta
 
-        wrate=rate_1step(yr, theta)
-
         wrate1=rate1_2step(ya, yx, theta)
 
         wrate2=rate2_2step(yx, theta)
 
        S_L=S_L+wrate1*hx
       ENDDO
-      
+
+      else
+          WRITE(*,*) 'ERROR, UNDEFINED REACTION TYPE ', reaction_type
+          stop
+      end if
+
       WRITE(*,'(a31,e14.8)') ' INTEGRAL( Wrate x dx ) => Sc :',S_L
 
       CALL dfnonp(nx,hx,ux(1,:),dux(1,:),1,1)
@@ -280,7 +296,7 @@
        maxdy=MAX(ABS(dy),maxdy)
       ENDDO
       del_f=1./maxdy
-       
+
       WRITE(*,'(a13,e14.8,a25,e14.8)') ' Grid size : ',hx,' / Laminar flame speed : ',u(1)
       WRITE(*,'(a19,e14.8,a3,f9.5,a20)') &
        ' Flame thickness : ',del_f,' / ',del_f/hx,' grids in the flame.'