diff --git a/include/sourmash.h b/include/sourmash.h
index 8e80d22834..d95dd07888 100644
--- a/include/sourmash.h
+++ b/include/sourmash.h
@@ -13,6 +13,8 @@ enum HashFunctions {
   HASH_FUNCTIONS_MURMUR64_PROTEIN = 2,
   HASH_FUNCTIONS_MURMUR64_DAYHOFF = 3,
   HASH_FUNCTIONS_MURMUR64_HP = 4,
+  HASH_FUNCTIONS_MURMUR64_SKIPM1N3 = 5,
+  HASH_FUNCTIONS_MURMUR64_SKIPM2N3 = 6,
 };
 typedef uint32_t HashFunctions;
 
@@ -274,6 +276,10 @@ double kmerminhash_similarity(const SourmashKmerMinHash *ptr,
                               bool ignore_abundance,
                               bool downsample);
 
+bool kmerminhash_skipm1n3(const SourmashKmerMinHash *ptr);
+
+bool kmerminhash_skipm2n3(const SourmashKmerMinHash *ptr);
+
 void kmerminhash_slice_free(uint64_t *ptr, uintptr_t insize);
 
 bool kmerminhash_track_abundance(const SourmashKmerMinHash *ptr);
diff --git a/src/core/src/ffi/minhash.rs b/src/core/src/ffi/minhash.rs
index baad446a0f..bb95242aa6 100644
--- a/src/core/src/ffi/minhash.rs
+++ b/src/core/src/ffi/minhash.rs
@@ -331,6 +331,18 @@ pub unsafe extern "C" fn kmerminhash_hp(ptr: *const SourmashKmerMinHash) -> bool
     mh.hp()
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn kmerminhash_skipm1n3(ptr: *const SourmashKmerMinHash) -> bool {
+    let mh = SourmashKmerMinHash::as_rust(ptr);
+    mh.skipm1n3()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn kmerminhash_skipm2n3(ptr: *const SourmashKmerMinHash) -> bool {
+    let mh = SourmashKmerMinHash::as_rust(ptr);
+    mh.skipm2n3()
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn kmerminhash_seed(ptr: *const SourmashKmerMinHash) -> u64 {
     let mh = SourmashKmerMinHash::as_rust(ptr);
diff --git a/src/core/src/ffi/mod.rs b/src/core/src/ffi/mod.rs
index 6f1dff78e4..dc8fb14c76 100644
--- a/src/core/src/ffi/mod.rs
+++ b/src/core/src/ffi/mod.rs
@@ -36,18 +36,23 @@ pub enum HashFunctions {
     Murmur64Protein = 2,
     Murmur64Dayhoff = 3,
     Murmur64Hp = 4,
+    Murmur64Skipm1n3 = 5,
+    Murmur64Skipm2n3 = 6,
 }
 
 impl From<HashFunctions> for crate::encodings::HashFunctions {
     fn from(v: HashFunctions) -> crate::encodings::HashFunctions {
         use crate::encodings::HashFunctions::{
-            Murmur64Dayhoff, Murmur64Dna, Murmur64Hp, Murmur64Protein,
+            Murmur64Dayhoff, Murmur64Dna, Murmur64Hp, Murmur64Protein, Murmur64Skipm1n3,
+            Murmur64Skipm2n3,
         };
         match v {
             HashFunctions::Murmur64Dna => Murmur64Dna,
             HashFunctions::Murmur64Protein => Murmur64Protein,
             HashFunctions::Murmur64Dayhoff => Murmur64Dayhoff,
             HashFunctions::Murmur64Hp => Murmur64Hp,
+            HashFunctions::Murmur64Skipm1n3 => Murmur64Skipm1n3,
+            HashFunctions::Murmur64Skipm2n3 => Murmur64Skipm2n3,
         }
     }
 }
@@ -55,13 +60,16 @@ impl From<HashFunctions> for crate::encodings::HashFunctions {
 impl From<crate::encodings::HashFunctions> for HashFunctions {
     fn from(v: crate::encodings::HashFunctions) -> HashFunctions {
         use crate::encodings::HashFunctions::{
-            Murmur64Dayhoff, Murmur64Dna, Murmur64Hp, Murmur64Protein,
+            Murmur64Dayhoff, Murmur64Dna, Murmur64Hp, Murmur64Protein, Murmur64Skipm1n3,
+            Murmur64Skipm2n3,
         };
         match v {
             Murmur64Dna => HashFunctions::Murmur64Dna,
             Murmur64Protein => HashFunctions::Murmur64Protein,
             Murmur64Dayhoff => HashFunctions::Murmur64Dayhoff,
             Murmur64Hp => HashFunctions::Murmur64Hp,
+            Murmur64Skipm1n3 => HashFunctions::Murmur64Skipm1n3,
+            Murmur64Skipm2n3 => HashFunctions::Murmur64Skipm2n3,
             _ => todo!("Not supported, probably custom"),
         }
     }
diff --git a/src/core/src/sketch/minhash.rs b/src/core/src/sketch/minhash.rs
index 43f8b602ea..d64efc63dc 100644
--- a/src/core/src/sketch/minhash.rs
+++ b/src/core/src/sketch/minhash.rs
@@ -723,6 +723,14 @@ impl KmerMinHash {
         self.hash_function == HashFunctions::Murmur64Hp
     }
 
+    pub fn skipm1n3(&self) -> bool {
+        self.hash_function == HashFunctions::Murmur64Skipm1n3
+    }
+
+    pub fn skipm2n3(&self) -> bool {
+        self.hash_function == HashFunctions::Murmur64Skipm2n3
+    }
+
     pub fn mins(&self) -> Vec<u64> {
         self.mins.clone()
     }
diff --git a/src/sourmash/cli/utils.py b/src/sourmash/cli/utils.py
index 26da5ead5f..467ed307fb 100644
--- a/src/sourmash/cli/utils.py
+++ b/src/sourmash/cli/utils.py
@@ -50,6 +50,39 @@ def add_moltype_args(parser):
     )
     parser.set_defaults(hp=False)
 
+    parser.add_argument(
+        "--skipm1n3",
+        "--skipmer-m1n3",
+        dest="skipm1n3",
+        action="store_true",
+        help="choose skipmer (m1n3) signatures",
+    )
+
+    parser.add_argument(
+        "--no-skipm1n3",
+        "--no-skipmer-m1n3",
+        dest="skipm1n3",
+        action="store_false",
+        help="do not choose skipmer (m1n3) signatures",
+    )
+    parser.set_defaults(skipm1n3=False)
+
+    parser.add_argument(
+        "--skipm2n3",
+        "--skipmer-m2n3",
+        dest="skipm2n3",
+        action="store_true",
+        help="choose skipmer (m2n3) signatures",
+    )
+    parser.add_argument(
+        "--no-skipm2n3",
+        "--no-skipmer-m2n3",
+        dest="skipm2n3",
+        action="store_false",
+        help="do not choose skipmer (m2n3) signatures",
+    )
+    parser.set_defaults(skipm2n3=False)
+
     parser.add_argument(
         "--dna",
         "--rna",
diff --git a/src/sourmash/index/__init__.py b/src/sourmash/index/__init__.py
index a8a638653d..b04952d873 100644
--- a/src/sourmash/index/__init__.py
+++ b/src/sourmash/index/__init__.py
@@ -1242,7 +1242,7 @@ def _check_select_parameters(**kw):
 
     moltype = kw.get("moltype")
     if moltype is not None:
-        if moltype not in ["DNA", "protein", "dayhoff", "hp"]:
+        if moltype not in ["DNA", "protein", "dayhoff", "hp", "skipm1n3", "skipm2n3"]:
             raise ValueError(f"unknown moltype: {moltype}")
 
     scaled = kw.get("scaled")
diff --git a/src/sourmash/minhash.py b/src/sourmash/minhash.py
index 90d8244e2d..c036fa6c3d 100644
--- a/src/sourmash/minhash.py
+++ b/src/sourmash/minhash.py
@@ -196,6 +196,8 @@ def __init__(
         is_protein=False,
         dayhoff=False,
         hp=False,
+        skipm1n3=False,
+        skipm2n3=False,
         track_abundance=False,
         seed=MINHASH_DEFAULT_SEED,
         max_hash=0,
@@ -215,6 +217,8 @@ def __init__(
            * is_protein (default False) - aa k-mers
            * dayhoff (default False) - dayhoff encoding
            * hp (default False) - hydrophilic/hydrophobic aa
+           * skipm1n3 (default False) - skipmer (m1n3)
+           * skipm2n3 (default False) - skipmer (m2n3)
            * track_abundance (default False) - track hash multiplicity
            * mins (default None) - list of hashvals, or (hashval, abund) pairs
            * seed (default 42) - murmurhash seed
@@ -243,6 +247,10 @@ def __init__(
         elif is_protein:
             hash_function = lib.HASH_FUNCTIONS_MURMUR64_PROTEIN
             ksize = ksize * 3
+        elif skipm1n3:
+            hash_function = lib.HASH_FUNCTIONS_MURMUR64_SKIPM1N3
+        elif skipm2n3:
+            hash_function = lib.HASH_FUNCTIONS_MURMUR64_SKIPM2N3
         else:
             hash_function = lib.HASH_FUNCTIONS_MURMUR64_DNA
 
@@ -264,6 +272,8 @@ def __copy__(self):
             is_protein=self.is_protein,
             dayhoff=self.dayhoff,
             hp=self.hp,
+            skipm1n3=self.skipm1n3,
+            skipm2n3=self.skipm2n3,
             track_abundance=self.track_abundance,
             seed=self.seed,
             max_hash=self._max_hash,
@@ -279,12 +289,20 @@ def __getstate__(self):
         # note: we multiple ksize by 3 here so that
         # pickle protocols that bypass __setstate__ <coff numpy coff>
         # get a ksize that makes sense to the Rust layer. See #2262.
+        # CTB/NTP note: if you add things below, you might want to put
+        # them at the end, because we use internal indexes in a few places.
+        # see especially `_set_num_scaled()` in sig/__main__.my.
+        # My apologies.
         return (
             self.num,
-            self.ksize if self.is_dna else self.ksize * 3,
+            self.ksize
+            if self.is_dna or self.skipm1n3 or self.skipm2n3
+            else self.ksize * 3,
             self.is_protein,
             self.dayhoff,
             self.hp,
+            self.skipm1n3,
+            self.skipm2n3,
             self.hashes,
             None,
             self.track_abundance,
@@ -300,6 +318,8 @@ def __setstate__(self, tup):
             is_protein,
             dayhoff,
             hp,
+            skipm1n3,
+            skipm2n3,
             mins,
             _,
             track_abundance,
@@ -316,6 +336,10 @@ def __setstate__(self, tup):
             if hp
             else lib.HASH_FUNCTIONS_MURMUR64_PROTEIN
             if is_protein
+            else lib.HASH_FUNCTIONS_MURMUR64_SKIPM1N3
+            if skipm1n3
+            else lib.HASH_FUNCTIONS_MURMUR64_SKIPM2N3
+            if skipm2n3
             else lib.HASH_FUNCTIONS_MURMUR64_DNA
         )
 
@@ -340,6 +364,8 @@ def copy_and_clear(self):
             is_protein=self.is_protein,
             dayhoff=self.dayhoff,
             hp=self.hp,
+            skipm1n3=self.skipm1n3,
+            skipm2n3=self.skipm2n3,
             track_abundance=self.track_abundance,
             seed=self.seed,
             max_hash=self._max_hash,
@@ -461,7 +487,7 @@ def kmers_and_hashes(self, sequence, *, force=False, is_protein=False):
 
     def add_kmer(self, kmer):
         "Add a kmer into the sketch."
-        if self.is_dna:
+        if self.is_dna or self.skipm1n3 or self.skipm2n3:
             if len(kmer) != self.ksize:
                 raise ValueError(f"kmer to add is not {self.ksize} in length")
         else:
@@ -561,7 +587,9 @@ def scaled(self):
 
     @property
     def is_dna(self):
-        return not (self.is_protein or self.dayhoff or self.hp)
+        return not (
+            self.is_protein or self.dayhoff or self.hp or self.skipm1n3 or self.skipm2n3
+        )
 
     @property
     def is_protein(self):
@@ -575,10 +603,18 @@ def dayhoff(self):
     def hp(self):
         return self._methodcall(lib.kmerminhash_hp)
 
+    @property
+    def skipm1n3(self):
+        return self._methodcall(lib.kmerminhash_skipm1n3)
+
+    @property
+    def skipm2n3(self):
+        return self._methodcall(lib.kmerminhash_skipm2n3)
+
     @property
     def ksize(self):
         k = self._methodcall(lib.kmerminhash_ksize)
-        if not self.is_dna:
+        if not self.is_dna and not self.skipm1n3 and not self.skipm2n3:
             assert k % 3 == 0
             k = int(k / 3)
         return k
@@ -1051,6 +1087,10 @@ def moltype(self):  # TODO: test in minhash tests
             return "dayhoff"
         elif self.hp:
             return "hp"
+        elif self.skipm1n3:
+            return "skipm1n3"
+        elif self.skipm2n3:
+            return "skipm2n3"
         else:
             return "DNA"
 
@@ -1224,6 +1264,8 @@ def __setstate__(self, tup):
             is_protein,
             dayhoff,
             hp,
+            skipm1n3,
+            skipm2n3,
             mins,
             _,
             track_abundance,
@@ -1240,6 +1282,10 @@ def __setstate__(self, tup):
             if hp
             else lib.HASH_FUNCTIONS_MURMUR64_PROTEIN
             if is_protein
+            else lib.HASH_FUNCTIONS_MURMUR64_SKIPM1N3
+            if skipm1n3
+            else lib.HASH_FUNCTIONS_MURMUR64_SKIPM2N3
+            if skipm2n3
             else lib.HASH_FUNCTIONS_MURMUR64_DNA
         )
 
diff --git a/src/sourmash/sig/__main__.py b/src/sourmash/sig/__main__.py
index 0b97c84347..5809270284 100644
--- a/src/sourmash/sig/__main__.py
+++ b/src/sourmash/sig/__main__.py
@@ -102,7 +102,7 @@ def _set_num_scaled(mh, num, scaled):
     # Number of hashes is 0th parameter
     mh_params[0] = num
     # Scale is 8th parameter
-    mh_params[8] = _get_max_hash_for_scaled(scaled)
+    mh_params[10] = _get_max_hash_for_scaled(scaled)
     mh.__setstate__(mh_params)
     assert mh.num == num
     assert mh.scaled == scaled
diff --git a/src/sourmash/sourmash_args.py b/src/sourmash/sourmash_args.py
index 9f2068160a..20028fa921 100644
--- a/src/sourmash/sourmash_args.py
+++ b/src/sourmash/sourmash_args.py
@@ -84,7 +84,7 @@ def check_num_bounds(arg):
 
 def get_moltype(sig, require=False):
     mh = sig.minhash
-    if mh.moltype in ("DNA", "dayhoff", "hp", "protein"):
+    if mh.moltype in ("DNA", "dayhoff", "hp", "protein", "skipm1n3", "skipm2n3"):
         moltype = mh.moltype
     else:
         raise ValueError(f"unknown molecule type for sig {sig}")
@@ -109,9 +109,15 @@ def calculate_moltype(args, default=None):
         moltype = "protein"
         n += 1
 
+    if args.skipm1n3:
+        moltype = "skipm1n3"
+
+    if args.skipm2n3:
+        moltype = "skipm2n3"
+
     if n > 1:
         error(
-            "cannot specify more than one of --dna/--rna/--nucleotide/--protein/--hp/--dayhoff"
+            "cannot specify more than one of --dna/--rna/--nucleotide/--protein/--hp/--dayhoff/--skipm1n3/--skipm2n3"
         )
         sys.exit(-1)
 
@@ -185,11 +191,13 @@ def load_include_exclude_db_patterns(args):
 
         def search_pattern(vals):
             return any(pattern.search(val) for val in vals)
+
     elif args.exclude_db_pattern:
         pattern = re.compile(args.exclude_db_pattern, re.IGNORECASE)
 
         def search_pattern(vals):
             return all(not pattern.search(val) for val in vals)
+
     else:
         search_pattern = None