diff --git a/src/C-interface/ellblock/bml_allocate_ellblock.c b/src/C-interface/ellblock/bml_allocate_ellblock.c
index ca5138b4b..92392c52a 100644
--- a/src/C-interface/ellblock/bml_allocate_ellblock.c
+++ b/src/C-interface/ellblock/bml_allocate_ellblock.c
@@ -75,7 +75,7 @@ bml_get_block_sizes(
         {
             s_default_bsize[ib] = s_default_block_dim;
         }
-        s_default_bsize[s_nb - 1] = N % s_default_block_dim;
+        s_default_bsize[s_nb - 1] = N - s_default_block_dim * (s_nb - 1);
     }
     return s_default_bsize;
 }
@@ -224,6 +224,8 @@ bml_zero_matrix_ellblock(
     int M,
     bml_distribution_mode_t distrib_mode)
 {
+    assert(N >= M);
+
     bml_matrix_ellblock_t *A = NULL;
 
     switch (matrix_precision)
diff --git a/src/C-interface/ellblock/bml_allocate_ellblock_typed.c b/src/C-interface/ellblock/bml_allocate_ellblock_typed.c
index ea4c525c9..0b8129ede 100644
--- a/src/C-interface/ellblock/bml_allocate_ellblock_typed.c
+++ b/src/C-interface/ellblock/bml_allocate_ellblock_typed.c
@@ -105,7 +105,9 @@ void TYPED_FUNC(
                 A->indexb[ind - 1] = A->indexb[ind];
                 A->ptr_value[ind - 1] = A->ptr_value[ind];
             }
-            A->ptr_value[A->nnzb[ib] - 1] = NULL;
+            int ind = ROWMAJOR(ib, A->nnzb[ib] - 1, A->NB, A->MB);
+            A->ptr_value[ind] = NULL;
+            A->indexb[ind] = -1;
             break;
         }
     }