diff --git a/tests/linalg_test.py b/tests/linalg_test.py
index 41a391a3..f2bd3e60 100644
--- a/tests/linalg_test.py
+++ b/tests/linalg_test.py
@@ -51,6 +51,29 @@ def test_multi_dot():
             assert e.is_zero(), t
 
 
+def test_matmul_irregular_histories():
+    dim = 2
+    length = 500
+
+    standard_array = []
+    for i in range(dim ** 2):
+        standard_array.append(pe.Obs([np.random.normal(1.1, 0.2, length)], ['ens1']))
+    standard_matrix = np.array(standard_array).reshape((dim, dim))
+
+    for idl in [range(1, 501, 2), range(250, 273), [2, 8, 19, 20, 78]]:
+        irregular_array = []
+        for i in range(dim ** 2):
+            irregular_array.append(pe.Obs([np.random.normal(1.1, 0.2, len(idl))], ['ens1'], idl=[idl]))
+        irregular_matrix = np.array(irregular_array).reshape((dim, dim))
+
+        t1 = standard_matrix @ irregular_matrix
+        t2 = pe.linalg.matmul(standard_matrix, irregular_matrix)
+
+        assert np.all([o.is_zero() for o in (t1 - t2).ravel()])
+        assert np.all([o.is_merged for o in t1.ravel()])
+        assert np.all([o.is_merged for o in t2.ravel()])
+
+
 def test_matrix_inverse():
     content = []
     for t in range(9):