diff --git a/tests/samples/issue434.root b/tests/samples/issue434.root
new file mode 100644
index 00000000..8e44f957
Binary files /dev/null and b/tests/samples/issue434.root differ
diff --git a/tests/test_issues.py b/tests/test_issues.py
index be91df51..e7547b9b 100644
--- a/tests/test_issues.py
+++ b/tests/test_issues.py
@@ -391,3 +391,16 @@ def test_issue429(self):
         dtype = [(fix(x._fName), "float32" if type(x).__name__ == "TLeafF" else "int32") for x in branch._fLeaves]
         array = branch.array(uproot.asdtype(dtype + [("padding", "S4")]))
         assert (array["padding"] == b"\xff\xff\xff\xff").all()
+
+    def test_issue434(self):
+        f = uproot.open("tests/samples/issue434.root")
+        fromdtype = [("pmt", "u1"), ("tdc", "<u4"), ("tot", "u1")]
+        todtype = [("pmt", "u1"), ("tdc", ">u4"), ("tot", "u1")]
+        tree = f[b'KM3NET_TIMESLICE_L1'][b'KM3NETDAQ::JDAQTimeslice']
+        superframes = tree[b'vector<KM3NETDAQ::JDAQSuperFrame>']
+        hits_buffer = superframes[b'vector<KM3NETDAQ::JDAQSuperFrame>.buffer']
+        hits = hits_buffer.lazyarray(
+                uproot.asjagged(
+                    uproot.astable(
+                        uproot.asdtype(fromdtype, todtype)), skipbytes=6))
+        assert 486480 == hits['tdc'][0][0]
diff --git a/uproot/interp/numerical.py b/uproot/interp/numerical.py
index 33707b9b..03b0d5c3 100644
--- a/uproot/interp/numerical.py
+++ b/uproot/interp/numerical.py
@@ -17,6 +17,9 @@
 else:
     string_types = (str, bytes)
 
+BYTEORDER_INDICATORS = (">", "<", "=", "|", b">", b"<", b"=", b"|")
+
+
 def _dtypeshape(obj):
     out = ()
     while obj.subdtype is not None:
@@ -85,7 +88,9 @@ class asdtype(_asnumeric):
     def __init__(self, fromdtype, todtype=None):
         if isinstance(fromdtype, self.awkward.numpy.dtype):
             self.fromdtype = fromdtype
-        elif isinstance(fromdtype, string_types) and len(fromdtype) > 0 and fromdtype[0] in (">", "<", "=", "|", b">", b"<", b"=", b"|"):
+        elif isinstance(fromdtype, string_types) and len(fromdtype) > 0 and fromdtype[0] in BYTEORDER_INDICATORS:
+            self.fromdtype = self.awkward.numpy.dtype(fromdtype)
+        elif isinstance(fromdtype, list) and any(e[1][0] in BYTEORDER_INDICATORS for e in fromdtype):
             self.fromdtype = self.awkward.numpy.dtype(fromdtype)
         else:
             self.fromdtype = self.awkward.numpy.dtype(fromdtype).newbyteorder(">")
@@ -94,7 +99,9 @@ def __init__(self, fromdtype, todtype=None):
             self.todtype = self.fromdtype.newbyteorder("=")
         elif isinstance(todtype, self.awkward.numpy.dtype):
             self.todtype = todtype
-        elif isinstance(todtype, string_types) and len(todtype) > 0 and todtype[0] in (">", "<", "=", "|", b">", b"<", b"=", b"|"):
+        elif isinstance(todtype, string_types) and len(todtype) > 0 and todtype[0] in BYTEORDER_INDICATORS:
+            self.todtype = self.awkward.numpy.dtype(todtype)
+        elif isinstance(todtype, list) and any(e[1][0] in BYTEORDER_INDICATORS for e in todtype):
             self.todtype = self.awkward.numpy.dtype(todtype)
         else:
             self.todtype = self.awkward.numpy.dtype(todtype).newbyteorder("=")