diff --git a/src/ports/postgres/modules/linalg/matrix_ops.py_in b/src/ports/postgres/modules/linalg/matrix_ops.py_in
index 9f3215c..4fc9a15 100644
--- a/src/ports/postgres/modules/linalg/matrix_ops.py_in
+++ b/src/ports/postgres/modules/linalg/matrix_ops.py_in
@@ -227,7 +227,6 @@
 
 
 def get_dims(matrix, matrix_args, is_block=False):
-
     if is_block:
         block_dim = plpy.execute("""
             SELECT
@@ -287,12 +286,15 @@
         if row_dim != 0:
             rv = plpy.execute("""
                 SELECT
-                    (array_upper({matrix_args[val]}::float8[], 1) -
-                     array_lower({matrix_args[val]}::float8[], 1) + 1)
+                    DISTINCT(array_upper({matrix_args[val]}::float8[], 1) -
+                             array_lower({matrix_args[val]}::float8[], 1) + 1)
                     AS col_dim
                 FROM
                     {matrix}
                 """.format(matrix=matrix, matrix_args=matrix_args))
+            _assert(rv and len(rv) == 1,
+                    "dimensions mismatch: row_array.size() != vec.size(). "
+                    "Data contains different sized arrays")
             col_dim = rv[0]['col_dim']
         else:
             col_dim = 0