diff --git a/UserData.h b/UserData.h
index 2c09cca..f2b73e0 100644
--- a/UserData.h
+++ b/UserData.h
@@ -162,7 +162,8 @@ typedef struct UserDataTag{
 	double flamePosition[2];
 	double flameTime[2];
 	size_t nTimeSteps;
-
+	/*heat release rate (HRR) data */
+	double* HRRdata;
 } *UserData;
 UserData allocateUserData(FILE *input);
 void setSaneDefaults(UserData data);