diff --git a/docs/source/images/gui_01.png b/docs/source/images/gui_01.png
index b7b2cac..7bf2900 100644
Binary files a/docs/source/images/gui_01.png and b/docs/source/images/gui_01.png differ
diff --git a/docs/source/images/gui_02.png b/docs/source/images/gui_02.png
index db39c35..62d96d4 100644
Binary files a/docs/source/images/gui_02.png and b/docs/source/images/gui_02.png differ
diff --git a/pytc/indiv_models/binding_polynomial.py b/pytc/indiv_models/binding_polynomial.py
index 3417d6c..5097055 100644
--- a/pytc/indiv_models/binding_polynomial.py
+++ b/pytc/indiv_models/binding_polynomial.py
@@ -93,4 +93,4 @@ def dQ(self):
             self._fit_beta_array, self._fit_dH_array, S_conc_corr, self._T_conc, self._T_conc_free, 
             final_array)
 
-        return final_array
\ No newline at end of file
+        return final_array
diff --git a/setup.py b/setup.py
index e89189c..eb288b8 100644
--- a/setup.py
+++ b/setup.py
@@ -29,4 +29,4 @@
       install_requires=["matplotlib","scipy","numpy","emcee","corner"],
       classifiers=['Programming Language :: Python'],
       ext_modules=[ext],
-      include_dirs=numpy.distutils.misc_util.get_numpy_include_dirs())
\ No newline at end of file
+      include_dirs=numpy.distutils.misc_util.get_numpy_include_dirs())
diff --git a/src/binding_polynomial.c b/src/binding_polynomial.c
index 968ba8e..c4a3e4f 100644
--- a/src/binding_polynomial.c
+++ b/src/binding_polynomial.c
@@ -144,10 +144,17 @@ void *dQ(double *fit_beta_obj, double *fit_dH_obj, double *S_conc_corr, double *
 
     // num and denom arrays
     numerator = (double *)malloc(num_shots*sizeof(double));
+    if (numerator== NULL){
+        return NULL;
+    }
     for (i = 0; i < num_shots; i++){
         numerator[i] = 0.0;
     }
     denominator = (double *)malloc(num_shots*sizeof(double));
+    if (denominator == NULL){
+        return NULL;
+    }
+
     for (i = 0; i < num_shots; i++){
         denominator[i] = 1.0;
     }
@@ -211,16 +218,17 @@ void *dQ(double *fit_beta_obj, double *fit_dH_obj, double *S_conc_corr, double *
     if (avg_dH == NULL){
         return NULL;
     }
-    for (j = 0; j < num_shots; j++){
-        avg_dH[j] = numerator[j]/denominator[j];
+
+    for (i = 0; i < num_shots; i++){
+        avg_dH[i] = numerator[i]/denominator[i];
     }
     // avg_dh[1:]
     subset_first_dH = (double *)malloc(num_shots_reduced*sizeof(double));
     if (subset_first_dH == NULL){
         return NULL;
     }
-    for(j = 0; j < num_shots_reduced; j++){
-        subset_first_dH[j] = avg_dH[j+1];
+    for(i = 0; i < num_shots_reduced; i++){
+        subset_first_dH[i] = avg_dH[i+1];
     }
 
     // avg_dh[:-1]
@@ -228,8 +236,8 @@ void *dQ(double *fit_beta_obj, double *fit_dH_obj, double *S_conc_corr, double *
     if (subset_last_dH == NULL){
         return NULL;
     }
-    for(j = 0; j < num_shots_reduced; j++){
-        subset_last_dH[j] = avg_dH[j];
+    for(i = 0; i < num_shots_reduced; i++){
+        subset_last_dH[i] = avg_dH[i];
     }
 
     // avg_dh[1:]-avg_dh[:-1];
@@ -237,8 +245,8 @@ void *dQ(double *fit_beta_obj, double *fit_dH_obj, double *S_conc_corr, double *
     if (X == NULL){
         return NULL;
     }
-    for (j = 0; j < num_shots_reduced; j++){
-        X[j] = subset_first_dH[j] - subset_last_dH[j];
+    for (i = 0; i < num_shots_reduced; i++){
+        X[i] = subset_first_dH[i] - subset_last_dH[i];
     }
 
     // S_conc_corr[1:]
@@ -246,12 +254,12 @@ void *dQ(double *fit_beta_obj, double *fit_dH_obj, double *S_conc_corr, double *
     if (subset_s_conc == NULL){
         return NULL;
     }
-    for(j = 0; j < num_shots_reduced; j++){
-        subset_s_conc[j] = S_conc_corr[j+1];
+    for(i = 0; i < num_shots_reduced; i++){
+        subset_s_conc[i] = S_conc_corr[i+1];
     }
 
-    for(j = 0; j < num_shots_reduced; j++){
-        final_array[j] = cell_volume*subset_s_conc[j]*X[j] + dilution_heats[j];
+    for(i = 0; i < num_shots_reduced; i++){
+        final_array[i] = cell_volume*subset_s_conc[i]*X[i] + dilution_heats[i];
     }
 
     // clean up
@@ -263,4 +271,4 @@ void *dQ(double *fit_beta_obj, double *fit_dH_obj, double *S_conc_corr, double *
     free(subset_s_conc);
     free(numerator);
     free(denominator);
-}
\ No newline at end of file
+}