diff --git a/Makefile.am b/Makefile.am
index c92c86cc..f3e27587 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -48,6 +48,8 @@ checkdiff               = test/diff/diff_cp_d_3_n_4_p_2.sh \
 			  test/diff/diff_reals_dim0-chgvar.sh \
 			  test/diff/diff_reals_dim0-extract.sh \
 			  test/diff/diff_reals_dim0-swapvar.sh \
+			  test/diff/diff_choice-linear-form-qq.sh \
+			  test/diff/diff_choice-linear-form-qq-real-roots.sh \
 			  test/diff/diff_bug_empty_tracer.sh \
 			  test/diff/diff_bug_2nd_prime_bad.sh \
 			  test/diff/diff_bug_68.sh \
diff --git a/configure.ac b/configure.ac
index 5a4c6020..ec886f73 100644
--- a/configure.ac
+++ b/configure.ac
@@ -202,6 +202,12 @@ AC_CONFIG_LINKS([
  input_files/radical_shape-qq.ms:input_files/radical_shape-qq.ms
  output_files/radical_shape-qq.res:output_files/radical_shape-qq.res
  test/diff/diff_radical_shape-qq.sh:test/diff/diff_radical_shape-qq.sh
+ input_files/choice-linear-form-qq.ms:input_files/choice-linear-form-qq.ms
+ output_files/choice-linear-form-qq.res:output_files/choice-linear-form-qq.res
+ test/diff/diff_choice-linear-form-qq.sh:test/diff/diff_choice-linear-form-qq.sh
+ input_files/choice-linear-form-qq-real-roots.ms:input_files/choice-linear-form-qq-real-roots.ms
+ output_files/choice-linear-form-qq-real-roots.res:output_files/choice-linear-form-qq-real-roots.res
+ test/diff/diff_choice-linear-form-qq-real-roots.sh:test/diff/diff_choice-linear-form-qq-real-roots.sh
  input_files/reals_dim0.ms:input_files/reals_dim0.ms
  output_files/reals_dim0.res:output_files/reals_dim0.res
  output_files/reals_dim0.p256.res:output_files/reals_dim0.p256.res
diff --git a/input_files/choice-linear-form-qq-real-roots.ms b/input_files/choice-linear-form-qq-real-roots.ms
new file mode 100644
index 00000000..21a609ae
--- /dev/null
+++ b/input_files/choice-linear-form-qq-real-roots.ms
@@ -0,0 +1,11 @@
+_xx[1], _xx[2], _xx[3], _xx[4], _xx[5], _xx[6], _xx[7], _xx[8] 
+0
+-_xx[1]+_xx[2],
+-_xx[1]+_xx[4],
+-_xx[1]+_xx[5],
+_xx[1]+_xx[6],
+-_xx[1]+_xx[7],
+-_xx[3]*_xx[6]+_xx[2]*_xx[7]+_xx[1],
+-_xx[4]*_xx[7]-_xx[1]+_xx[3],
+-_xx[5]*_xx[6]+_xx[2]*_xx[8]-_xx[1]+_xx[6]-_xx[8],
+-_xx[4]*_xx[6]+_xx[5]*_xx[6]-_xx[2]*_xx[8]+_xx[4]*_xx[8]+_xx[2]-_xx[5]
diff --git a/input_files/choice-linear-form-qq.ms b/input_files/choice-linear-form-qq.ms
new file mode 100644
index 00000000..21a609ae
--- /dev/null
+++ b/input_files/choice-linear-form-qq.ms
@@ -0,0 +1,11 @@
+_xx[1], _xx[2], _xx[3], _xx[4], _xx[5], _xx[6], _xx[7], _xx[8] 
+0
+-_xx[1]+_xx[2],
+-_xx[1]+_xx[4],
+-_xx[1]+_xx[5],
+_xx[1]+_xx[6],
+-_xx[1]+_xx[7],
+-_xx[3]*_xx[6]+_xx[2]*_xx[7]+_xx[1],
+-_xx[4]*_xx[7]-_xx[1]+_xx[3],
+-_xx[5]*_xx[6]+_xx[2]*_xx[8]-_xx[1]+_xx[6]-_xx[8],
+-_xx[4]*_xx[6]+_xx[5]*_xx[6]-_xx[2]*_xx[8]+_xx[4]*_xx[8]+_xx[2]-_xx[5]
diff --git a/output_files/choice-linear-form-qq-real-roots.res b/output_files/choice-linear-form-qq-real-roots.res
new file mode 100644
index 00000000..bea02a67
--- /dev/null
+++ b/output_files/choice-linear-form-qq-real-roots.res
@@ -0,0 +1,3 @@
+[0, [1,
+[[[-1, -1], [-1, -1], [0, 0], [-1, -1], [-1, -1], [1, 1], [-1, -1], [3 / 2, 3 / 2]], [[0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0]]]
+]]:
diff --git a/output_files/choice-linear-form-qq.res b/output_files/choice-linear-form-qq.res
new file mode 100644
index 00000000..ff593ec7
--- /dev/null
+++ b/output_files/choice-linear-form-qq.res
@@ -0,0 +1,26 @@
+[0, [0, 
+9, 
+3, 
+['_xx[1]', '_xx[2]', '_xx[3]', '_xx[4]', '_xx[5]', '_xx[6]', '_xx[7]', '_xx[8]', 'A'],
+[1,4,9,16,25,36,49,64,1],
+[1,
+[[2, [0, 37, 1]],
+[1, [37, 2]],
+[
+[[1, [0, 1]],
+1],
+[[1, [0, 1]],
+1],
+[[1, [0, 0]],
+1],
+[[1, [0, 1]],
+1],
+[[1, [0, 1]],
+1],
+[[1, [0, -1]],
+1],
+[[1, [0, 1]],
+1],
+[[1, [0, -3]],
+2]
+]]]]]:
diff --git a/src/fglm/fglm_core.c b/src/fglm/fglm_core.c
index 7bb52c6d..14e8ec5c 100644
--- a/src/fglm/fglm_core.c
+++ b/src/fglm/fglm_core.c
@@ -1154,7 +1154,6 @@ static inline int invert_table_polynomial (param_t *param,
     if (lambda == 0) {
       nmod_poly_set_coeff_ui (data_bms->BMS->R0,i,
 			      data->res[(length-i-1)*block_size+ncoord]);
-
     }
     else {
       uint64_t coeff= (lambda*data->res[(length-i-1)*block_size]) % prime;
@@ -1165,6 +1164,8 @@ static inline int invert_table_polynomial (param_t *param,
 
   }
 
+  nmod_poly_zero(data_bms->BMS->R1);
+
   nmod_poly_mul (data_bms->Z1,data_bms->BMS->R0,data_bms->BMS->V1);
   nmod_poly_shift_right (data_bms->Z1,data_bms->Z1,length);
   nmod_poly_xgcd (data_bms->BMS->R0,data_bms->BMS->R1,data_bms->Z2,param->elim,
@@ -1186,6 +1187,7 @@ static inline void divide_table_polynomials (param_t *param,
   szmat_t length= data_bms->BMS->V1->length-1;
   nmod_poly_zero (data_bms->BMS->R0);
   nmod_poly_fit_length(data_bms->BMS->R0, length);
+  nmod_poly_zero(data_bms->BMS->R1);
 
   for (long i = 0; i < length; i++){
     if (lambda == 0) {
@@ -1268,6 +1270,7 @@ int compute_parametrizations_non_shape_position_case(param_t *param,
     fprintf(stdout, "invC1=");
     nmod_poly_fprint_pretty (stdout, data_bms->Z2, "x"); fprintf (stdout,"\n");
 #endif
+
     long dec = 0;
 
     for(long nc = 0; nc < nvars - 1 ; nc++){
diff --git a/src/msolve/msolve.c b/src/msolve/msolve.c
index c4a9b6be..2c6fb374 100644
--- a/src/msolve/msolve.c
+++ b/src/msolve/msolve.c
@@ -1586,6 +1586,18 @@ static int32_t check_for_single_element_groebner_basis(
   return empty_solution_set;
 }
 
+/*
+ * returns 1 if the parametrizations are the same else it returns 0
+ * */
+static int equal_param(param_t *param, param_t *test_param){
+  for(int i = 0; i < param->nvars-1; i++){
+    if(!nmod_poly_equal(param->coords[i], test_param->coords[i])){
+      return 0;
+    }
+  }
+  return 1;
+}
+
 static int32_t *initial_modular_step(
         sp_matfglm_t **bmatrix,
         int32_t **bdiv_xn,
@@ -1695,6 +1707,19 @@ static int32_t *initial_modular_step(
             *bparam = nmod_fglm_compute_trace_data(*bmatrix, fc, bs->ht->nv,
                     *bsz, *nlins_ptr, linvars, lineqs_ptr[0], squvars,
                     md->info_level, bdata_fglm, bdata_bms, success, md);
+            if((*bparam)->elim->length - 1 != dquot){
+              param_t **test_nmod_param =
+                    (param_t **)malloc(sizeof(param_t *));
+              *test_nmod_param = nmod_fglm_compute_trace_data(*bmatrix, fc, bs->ht->nv,
+                      *bsz, *nlins_ptr, linvars, lineqs_ptr[0], squvars,
+                      0, bdata_fglm, bdata_bms, success, md);
+              int boo = equal_param(*bparam, *test_nmod_param);
+              if(boo == 0){
+                *success = 0;
+              }
+              free_fglm_param(test_nmod_param[0]);
+              free(test_nmod_param);
+            }
         }
         *dim = 0;
         *dquot_ori = dquot;
diff --git a/test/diff/diff_choice-linear-form-qq-real-roots.sh b/test/diff/diff_choice-linear-form-qq-real-roots.sh
new file mode 100755
index 00000000..ce544eee
--- /dev/null
+++ b/test/diff/diff_choice-linear-form-qq-real-roots.sh
@@ -0,0 +1,50 @@
+#!/bin/bash
+
+file=choice-linear-form-qq-real-roots
+
+
+$(pwd)/msolve -f input_files/$file.ms -o test/diff/$file.res \
+      -d 0 -l 2 -t 1
+if [ $? -gt 0 ]; then
+    exit 1
+fi
+
+diff test/diff/$file.res output_files/$file.res
+if [ $? -gt 0 ]; then
+    exit 2
+fi
+
+$(pwd)/msolve -f input_files/$file.ms -o test/diff/$file.res \
+      -d 0 -l 2 -t 2
+if [ $? -gt 0 ]; then
+    exit 21
+fi
+
+diff test/diff/$file.res output_files/$file.res
+if [ $? -gt 0 ]; then
+    exit 22
+fi
+
+$(pwd)/msolve -f input_files/$file.ms -o test/diff/$file.res \
+      -d 0 -l 44 -t 1
+if [ $? -gt 0 ]; then
+    exit 41
+fi
+
+diff test/diff/$file.res output_files/$file.res
+if [ $? -gt 0 ]; then
+    exit 42
+fi
+
+$(pwd)/msolve -f input_files/$file.ms -o test/diff/$file.res \
+      -d 0 -l 44 -t 2
+if [ $? -gt 0 ]; then
+    exit 61
+fi
+
+diff test/diff/$file.res output_files/$file.res
+if [ $? -gt 0 ]; then
+    exit 62
+fi
+
+rm test/diff/$file.res
diff --git a/test/diff/diff_choice-linear-form-qq.sh b/test/diff/diff_choice-linear-form-qq.sh
new file mode 100755
index 00000000..6850588a
--- /dev/null
+++ b/test/diff/diff_choice-linear-form-qq.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+
+file=choice-linear-form-qq
+
+source test/diff/diff_source.sh