diff --git a/tests/parser/test_selector_table.py b/tests/parser/test_selector_table.py
index 01a83698b7..3ac50707c2 100644
--- a/tests/parser/test_selector_table.py
+++ b/tests/parser/test_selector_table.py
@@ -10,6 +10,437 @@
 from vyper.compiler.settings import OptimizationLevel
 
 
+def test_dense_selector_table_empty_buckets(get_contract):
+    # some special combination of selectors which can result in
+    # some empty bucket being returned from _mk_buckets (that is,
+    # len(_mk_buckets(..., n_buckets)) != n_buckets
+    code = """
+@external
+def aX61QLPWF()->uint256:
+    return 1
+@external
+def aQHG0P2L1()->uint256:
+    return 2
+@external
+def a2G8ME94W()->uint256:
+    return 3
+@external
+def a0GNA21AY()->uint256:
+    return 4
+@external
+def a4U1XA4T5()->uint256:
+    return 5
+@external
+def aAYLMGOBZ()->uint256:
+    return 6
+@external
+def a0KXRLHKE()->uint256:
+    return 7
+@external
+def aDQS32HTR()->uint256:
+    return 8
+@external
+def aP4K6SA3S()->uint256:
+    return 9
+@external
+def aEB94ZP5S()->uint256:
+    return 10
+@external
+def aTOIMN0IM()->uint256:
+    return 11
+@external
+def aXV2N81OW()->uint256:
+    return 12
+@external
+def a66PP6Y5X()->uint256:
+    return 13
+@external
+def a5MWMTEWN()->uint256:
+    return 14
+@external
+def a5ZFST4Z8()->uint256:
+    return 15
+@external
+def aR13VXULX()->uint256:
+    return 16
+@external
+def aWITH917Y()->uint256:
+    return 17
+@external
+def a59NP6C5O()->uint256:
+    return 18
+@external
+def aJ02590EX()->uint256:
+    return 19
+@external
+def aUAXAAUQ8()->uint256:
+    return 20
+@external
+def aWR1XNC6J()->uint256:
+    return 21
+@external
+def aJABKZOKH()->uint256:
+    return 22
+@external
+def aO1TT0RJT()->uint256:
+    return 23
+@external
+def a41442IOK()->uint256:
+    return 24
+@external
+def aMVXV9FHQ()->uint256:
+    return 25
+@external
+def aNN0KJDZM()->uint256:
+    return 26
+@external
+def aOX965047()->uint256:
+    return 27
+@external
+def a575NX2J3()->uint256:
+    return 28
+@external
+def a16EN8O7W()->uint256:
+    return 29
+@external
+def aSZXLFF7O()->uint256:
+    return 30
+@external
+def aQKQCIPH9()->uint256:
+    return 31
+@external
+def aIP8021DL()->uint256:
+    return 32
+@external
+def aQAV0HSHX()->uint256:
+    return 33
+@external
+def aZVPAD745()->uint256:
+    return 34
+@external
+def aJYBSNST4()->uint256:
+    return 35
+@external
+def aQGWC4NYQ()->uint256:
+    return 36
+@external
+def aFMBB9CXJ()->uint256:
+    return 37
+@external
+def aYWM7ZUH1()->uint256:
+    return 38
+@external
+def aJAZONIX1()->uint256:
+    return 39
+@external
+def aQZ1HJK0H()->uint256:
+    return 40
+@external
+def aKIH9LOUB()->uint256:
+    return 41
+@external
+def aF4ZT80XL()->uint256:
+    return 42
+@external
+def aYQD8UKR5()->uint256:
+    return 43
+@external
+def aP6NCCAI4()->uint256:
+    return 44
+@external
+def aY92U2EAZ()->uint256:
+    return 45
+@external
+def aHMQ49D7P()->uint256:
+    return 46
+@external
+def aMC6YX8VF()->uint256:
+    return 47
+@external
+def a734X6YSI()->uint256:
+    return 48
+@external
+def aRXXPNSMU()->uint256:
+    return 49
+@external
+def aL5XKDTGT()->uint256:
+    return 50
+@external
+def a86V1Y18A()->uint256:
+    return 51
+@external
+def aAUM8PL5J()->uint256:
+    return 52
+@external
+def aBAEC1ERZ()->uint256:
+    return 53
+@external
+def a1U1VA3UE()->uint256:
+    return 54
+@external
+def aC9FGVAHC()->uint256:
+    return 55
+@external
+def aWN81WYJ3()->uint256:
+    return 56
+@external
+def a3KK1Y07J()->uint256:
+    return 57
+@external
+def aAZ6P6OSG()->uint256:
+    return 58
+@external
+def aWP5HCIB3()->uint256:
+    return 59
+@external
+def aVEK161C5()->uint256:
+    return 60
+@external
+def aY0Q3O519()->uint256:
+    return 61
+@external
+def aDHHHFIAE()->uint256:
+    return 62
+@external
+def aGSJBCZKQ()->uint256:
+    return 63
+@external
+def aZQQIUDHY()->uint256:
+    return 64
+@external
+def a12O9QDH5()->uint256:
+    return 65
+@external
+def aRQ1178XR()->uint256:
+    return 66
+@external
+def aDT25C832()->uint256:
+    return 67
+@external
+def aCSB01C4E()->uint256:
+    return 68
+@external
+def aYGBPKZSD()->uint256:
+    return 69
+@external
+def aP24N3EJ8()->uint256:
+    return 70
+@external
+def a531Y9X3C()->uint256:
+    return 71
+@external
+def a4727IKVS()->uint256:
+    return 72
+@external
+def a2EX1L2BS()->uint256:
+    return 73
+@external
+def a6145RN68()->uint256:
+    return 74
+@external
+def aDO1ZNX97()->uint256:
+    return 75
+@external
+def a3R28EU6M()->uint256:
+    return 76
+@external
+def a9BFC867L()->uint256:
+    return 77
+@external
+def aPL1MBGYC()->uint256:
+    return 78
+@external
+def aI6H11O48()->uint256:
+    return 79
+@external
+def aX0248DZY()->uint256:
+    return 80
+@external
+def aE4JBUJN4()->uint256:
+    return 81
+@external
+def aXBDB2ZBO()->uint256:
+    return 82
+@external
+def a7O7MYYHL()->uint256:
+    return 83
+@external
+def aERFF4PB6()->uint256:
+    return 84
+@external
+def aJCUBG6TJ()->uint256:
+    return 85
+@external
+def aQ5ELXM0F()->uint256:
+    return 86
+@external
+def aWDT9UQVV()->uint256:
+    return 87
+@external
+def a7UU40DJK()->uint256:
+    return 88
+@external
+def aH01IT5VS()->uint256:
+    return 89
+@external
+def aSKYTZ0FC()->uint256:
+    return 90
+@external
+def aNX5LYRAW()->uint256:
+    return 91
+@external
+def aUDKAOSGG()->uint256:
+    return 92
+@external
+def aZ86YGAAO()->uint256:
+    return 93
+@external
+def aIHWQGKLO()->uint256:
+    return 94
+@external
+def aKIKFLAR9()->uint256:
+    return 95
+@external
+def aCTPE0KRS()->uint256:
+    return 96
+@external
+def aAD75X00P()->uint256:
+    return 97
+@external
+def aDROUEF2F()->uint256:
+    return 98
+@external
+def a8CDIF6YN()->uint256:
+    return 99
+@external
+def aD2X7TM83()->uint256:
+    return 100
+@external
+def a3W5UUB4L()->uint256:
+    return 101
+@external
+def aG4MOBN4B()->uint256:
+    return 102
+@external
+def aPRS0MSG7()->uint256:
+    return 103
+@external
+def aKN3GHBUR()->uint256:
+    return 104
+@external
+def aGE435RHQ()->uint256:
+    return 105
+@external
+def a4E86BNFE()->uint256:
+    return 106
+@external
+def aYDG928YW()->uint256:
+    return 107
+@external
+def a2HFP5GQE()->uint256:
+    return 108
+@external
+def a5DPMVXKA()->uint256:
+    return 109
+@external
+def a3OFVC3DR()->uint256:
+    return 110
+@external
+def aK8F62DAN()->uint256:
+    return 111
+@external
+def aJS9EY3U6()->uint256:
+    return 112
+@external
+def aWW789JQH()->uint256:
+    return 113
+@external
+def a8AJJN3YR()->uint256:
+    return 114
+@external
+def a4D0MUIDU()->uint256:
+    return 115
+@external
+def a35W41JQR()->uint256:
+    return 116
+@external
+def a07DQOI1E()->uint256:
+    return 117
+@external
+def aFT43YNCT()->uint256:
+    return 118
+@external
+def a0E75I8X3()->uint256:
+    return 119
+@external
+def aT6NXIRO4()->uint256:
+    return 120
+@external
+def aXB2UBAKQ()->uint256:
+    return 121
+@external
+def aHWH55NW6()->uint256:
+    return 122
+@external
+def a7TCFE6C2()->uint256:
+    return 123
+@external
+def a8XYAM81I()->uint256:
+    return 124
+@external
+def aHQTQ4YBY()->uint256:
+    return 125
+@external
+def aGCZEHG6Y()->uint256:
+    return 126
+@external
+def a6LJTKIW0()->uint256:
+    return 127
+@external
+def aBDIXTD9S()->uint256:
+    return 128
+@external
+def aCB83G21P()->uint256:
+    return 129
+@external
+def aZC525N4K()->uint256:
+    return 130
+@external
+def a40LC94U6()->uint256:
+    return 131
+@external
+def a8X9TI93D()->uint256:
+    return 132
+@external
+def aGUG9CD8Y()->uint256:
+    return 133
+@external
+def a0LAERVAY()->uint256:
+    return 134
+@external
+def aXQ0UEX19()->uint256:
+    return 135
+@external
+def aKK9C7NE7()->uint256:
+    return 136
+@external
+def aS2APW8UE()->uint256:
+    return 137
+@external
+def a65NT07MM()->uint256:
+    return 138
+@external
+def aGRMT6ZW5()->uint256:
+    return 139
+@external
+def aILR4U1Z()->uint256:
+    return 140
+    """
+    c = get_contract(code)
+
+    assert c.aX61QLPWF() == 1  # will revert if the header section is misaligned
+
+
 @given(
     n_methods=st.integers(min_value=1, max_value=100),
     seed=st.integers(min_value=0, max_value=2**64 - 1),
diff --git a/vyper/codegen/jumptable_utils.py b/vyper/codegen/jumptable_utils.py
index 6987ce90bd..6404b75532 100644
--- a/vyper/codegen/jumptable_utils.py
+++ b/vyper/codegen/jumptable_utils.py
@@ -43,7 +43,11 @@ def _image_of(xs, magic):
     return [((x * magic) >> bits_shift) % len(xs) for x in xs]
 
 
-class _Failure(Exception):
+class _FindMagicFailure(Exception):
+    pass
+
+
+class _HasEmptyBuckets(Exception):
     pass
 
 
@@ -53,7 +57,7 @@ def find_magic_for(xs):
         if len(test) == len(set(test)):
             return m
 
-    raise _Failure(f"Could not find hash for {xs}")
+    raise _FindMagicFailure(f"Could not find hash for {xs}")
 
 
 def _mk_buckets(method_ids, n_buckets):
@@ -72,6 +76,11 @@ def _mk_buckets(method_ids, n_buckets):
 def _dense_jumptable_info(method_ids, n_buckets):
     buckets = _mk_buckets(method_ids, n_buckets)
 
+    # if there are somehow empty buckets, bail out as that can mess up
+    # the bucket header layout
+    if len(buckets) != n_buckets:
+        raise _HasEmptyBuckets()
+
     ret = {}
     for bucket_id, method_ids in buckets.items():
         magic = find_magic_for(method_ids)
@@ -98,8 +107,16 @@ def generate_dense_jumptable_info(signatures):
     while n_buckets > 0:
         try:
             # print(f"trying {n_buckets} (bucket size {n // n_buckets})")
-            ret = _dense_jumptable_info(method_ids, n_buckets)
-        except _Failure:
+            solution = _dense_jumptable_info(method_ids, n_buckets)
+            assert len(solution) == n_buckets
+            ret = n_buckets, solution
+
+        except _HasEmptyBuckets:
+            # found a solution which has empty buckets; skip it since
+            # it will break the bucket layout.
+            pass
+
+        except _FindMagicFailure:
             if ret is not None:
                 break
 
diff --git a/vyper/codegen/module.py b/vyper/codegen/module.py
index 8caea9ee9b..6445a5e1e0 100644
--- a/vyper/codegen/module.py
+++ b/vyper/codegen/module.py
@@ -124,8 +124,12 @@ def _selector_section_dense(external_functions, global_ctx):
         ir_node = ["label", label, ["var_list"], entry_point.ir_node]
         function_irs.append(IRnode.from_list(ir_node))
 
-    jumptable_info = jumptable_utils.generate_dense_jumptable_info(entry_points.keys())
-    n_buckets = len(jumptable_info)
+    n_buckets, jumptable_info = jumptable_utils.generate_dense_jumptable_info(entry_points.keys())
+    # note: we are guaranteed by jumptable_utils that there are no buckets
+    # which are empty. sanity check that the bucket ids are well-behaved:
+    assert n_buckets == len(jumptable_info)
+    for i, (bucket_id, _) in enumerate(sorted(jumptable_info.items())):
+        assert i == bucket_id
 
     #  bucket magic <2 bytes> | bucket location <2 bytes> | bucket size <1 byte>
     # TODO: can make it smaller if the largest bucket magic <= 255