diff --git a/sourmash_lib/test-data/benchmark.dna.sig b/sourmash_lib/test-data/benchmark.dna.sig
new file mode 100644
index 000000000..0b1fa4b16
--- /dev/null
+++ b/sourmash_lib/test-data/benchmark.dna.sig
@@ -0,0 +1,137 @@
+class: sourmash_signature
+email: ''
+hash_function: 0.murmur64
+name: gi|556503834:337-2799 Escherichia coli str. K-12 substr. MG1655, complete genome
+signatures:
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+  md5sum: 3b3f65dba0dad5429f45e7023e269d7c
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+  num: 500
+type: mrnaseq
+version: 0.4
+---
+
diff --git a/sourmash_lib/test-data/benchmark.input_prot.sig b/sourmash_lib/test-data/benchmark.input_prot.sig
new file mode 100644
index 000000000..db14d0c44
--- /dev/null
+++ b/sourmash_lib/test-data/benchmark.input_prot.sig
@@ -0,0 +1,139 @@
+class: sourmash_signature
+email: ''
+hash_function: 0.murmur64
+name: NP_414543.1 Bifunctional aspartokinase/homoserine dehydrogenase 1 [Escherichia
+  coli str. K-12 substr. MG1655]
+signatures:
+- ksize: 21
+  md5sum: 24edfd6d0f64fbf42dbccb93c8c134f7
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+    10662675238870589643, 10666054824191775732, 10676845122526014730, 10704087553262149467]
+  molecule: protein
+  num: 500
+type: mrnaseq
+version: 0.4
+---
+
diff --git a/sourmash_lib/test-data/benchmark.prot.sig b/sourmash_lib/test-data/benchmark.prot.sig
new file mode 100644
index 000000000..a655117b0
--- /dev/null
+++ b/sourmash_lib/test-data/benchmark.prot.sig
@@ -0,0 +1,137 @@
+class: sourmash_signature
+email: ''
+hash_function: 0.murmur64
+name: gi|556503834:337-2799 Escherichia coli str. K-12 substr. MG1655, complete genome
+signatures:
+- ksize: 21
+  md5sum: c567e8c26e673ec982a4939da58ffaa6
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+    1934577446354899030, 1938113130056821616, 1942655715581533824, 1943542560170639744,
+    1949049296707212374, 1950730322789272536, 1958274760512308516, 1959812964369970361]
+  molecule: protein
+  num: 500
+type: mrnaseq
+version: 0.4
+---
+
diff --git a/sourmash_lib/test_sourmash.py b/sourmash_lib/test_sourmash.py
index 788c80325..9557c259a 100644
--- a/sourmash_lib/test_sourmash.py
+++ b/sourmash_lib/test_sourmash.py
@@ -282,6 +282,74 @@ def test_do_sourmash_check_protein_comparisons():
         assert round(sig2_aa.similarity(sig2_trans), 3) == 0.0
 
 
+def test_do_sourmash_check_knowngood_dna_comparisons():
+    # this test checks against a known good signature calculated
+    # by utils/compute-dna-mh-another-way.py
+    with utils.TempDirectory() as location:
+        testdata1 = utils.get_test_data('ecoli.genes.fna')
+        status, out, err = utils.runscript('sourmash',
+                                           ['compute', '-k', '21',
+                                            '--singleton', '--dna',
+                                            testdata1],
+                                           in_directory=location)
+        sig1 = os.path.join(location, 'ecoli.genes.fna.sig')
+        assert os.path.exists(sig1)
+
+        x = list(signature.load_signatures(sig1))
+        sig1, sig2 = sorted(x, key=lambda x: x.name())
+
+        knowngood = utils.get_test_data('benchmark.dna.sig')
+        good = list(signature.load_signatures(knowngood))[0]
+
+        assert sig2.similarity(good) == 1.0
+
+
+def test_do_sourmash_check_knowngood_input_protein_comparisons():
+    # this test checks against a known good signature calculated
+    # by utils/compute-input-prot-another-way.py
+    with utils.TempDirectory() as location:
+        testdata1 = utils.get_test_data('ecoli.faa')
+        status, out, err = utils.runscript('sourmash',
+                                           ['compute', '-k', '21',
+                                            '--input-is-protein',
+                                            '--singleton',
+                                            testdata1],
+                                           in_directory=location)
+        sig1 = os.path.join(location, 'ecoli.faa.sig')
+        assert os.path.exists(sig1)
+
+        x = list(signature.load_signatures(sig1))
+        sig1_aa, sig2_aa = sorted(x, key=lambda x: x.name())
+
+        knowngood = utils.get_test_data('benchmark.input_prot.sig')
+        good_aa = list(signature.load_signatures(knowngood))[0]
+
+        assert sig1_aa.similarity(good_aa) == 1.0
+
+
+def test_do_sourmash_check_knowngood_protein_comparisons():
+    # this test checks against a known good signature calculated
+    # by utils/compute-prot-mh-another-way.py
+    with utils.TempDirectory() as location:
+        testdata1 = utils.get_test_data('ecoli.genes.fna')
+        status, out, err = utils.runscript('sourmash',
+                                           ['compute', '-k', '21',
+                                            '--singleton', '--protein',
+                                            '--no-dna',
+                                            testdata1],
+                                           in_directory=location)
+        sig1 = os.path.join(location, 'ecoli.genes.fna.sig')
+        assert os.path.exists(sig1)
+
+        x = list(signature.load_signatures(sig1))
+        sig1_trans, sig2_trans = sorted(x, key=lambda x: x.name())
+
+        knowngood = utils.get_test_data('benchmark.prot.sig')
+        good_trans = list(signature.load_signatures(knowngood))[0]
+
+        assert sig2_trans.similarity(good_trans) == 1.0
+
+
 def test_do_plot_comparison():
     with utils.TempDirectory() as location:
         testdata1 = utils.get_test_data('short.fa')
diff --git a/utils/compute-dna-mh-another-way.py b/utils/compute-dna-mh-another-way.py
new file mode 100755
index 000000000..e9a8d996e
--- /dev/null
+++ b/utils/compute-dna-mh-another-way.py
@@ -0,0 +1,60 @@
+#! /usr/bin/env python
+"""
+Use the MurmurHash library mmh3 and separate Python code to calculate
+a MinHash signature for input DNA sequence, as a way to do an
+external check on our C++ implementation.
+
+The output of this is used in test_sourmash.py to verify our C++ code.
+"""
+
+__complementTranslation = { "A": "T", "C": "G", "G": "C", "T": "A", "N": "N" }
+def complement(s):
+    """
+    Return complement of 's'.
+    """
+    c = "".join(__complementTranslation[n] for n in s)
+    return c
+
+
+def reverse(s):
+    """
+    Return reverse of 's'.
+    """
+    r = "".join(reversed(s))
+    return r
+
+
+def kmers(seq, k):
+    for start in range(len(seq) - k + 1):
+        yield seq[start:start + k]
+
+###
+
+K = 21
+
+import sys, screed
+import mmh3
+import sourmash_lib
+print('imported sourmash:', sourmash_lib, file=sys.stderr)
+from sourmash_lib import MinHash
+import sourmash_lib.signature
+
+record = next(iter(screed.open(sys.argv[1])))
+print('loaded', record.name, file=sys.stderr)
+revcomp = reverse(complement((record.sequence)))
+
+E = sourmash_lib.Estimators(ksize=K, n=500, protein=False)
+mh = E.mh
+
+for fwd_kmer in kmers(record.sequence, K):
+    rev_kmer = reverse(complement(fwd_kmer))
+    if fwd_kmer < rev_kmer:
+        kmer = fwd_kmer
+    else:
+        kmer = rev_kmer
+
+    hash = mmh3.hash128(kmer, seed=42)
+    mh.add_hash(hash)
+
+s = sourmash_lib.signature.SourmashSignature('', E, name=record.name)
+print(sourmash_lib.signature.save_signatures([s]))
diff --git a/utils/compute-input-prot-another-way.py b/utils/compute-input-prot-another-way.py
new file mode 100755
index 000000000..18282677c
--- /dev/null
+++ b/utils/compute-input-prot-another-way.py
@@ -0,0 +1,87 @@
+#! /usr/bin/env python
+"""
+Use the MurmurHash library mmh3 and separate Python code to calculate
+a MinHash signature for input protein sequence, as a way to do an
+external check on our C++ implementation.
+
+The output of this is used in test_sourmash.py to verify our C++ code.
+"""
+
+dna_to_aa={'TTT':'F','TTC':'F', 'TTA':'L','TTG':'L',
+                'TCT':'S','TCC':'S','TCA':'S','TCG':'S',
+                'TAT':'Y','TAC':'Y', 'TAA':'*','TAG':'*','TGA':'*',
+                'TGT':'C','TGC':'C', 'TGG':'W',
+                'CTT':'L','CTC':'L','CTA':'L','CTG':'L',
+                'CCT':'P','CCC':'P','CCA':'P','CCG':'P',
+                'CAT':'H','CAC':'H', 'CAA':'Q','CAG':'Q',
+                'CGT':'R','CGC':'R','CGA':'R','CGG':'R',
+                'ATT':'I','ATC':'I','ATA':'I', 'ATG':'M',
+                'ACT':'T','ACC':'T','ACA':'T','ACG':'T',
+                'AAT':'N','AAC':'N', 'AAA':'K','AAG':'K',
+                'AGT':'S','AGC':'S', 'AGA':'R','AGG':'R',
+                'GTT':'V','GTC':'V','GTA':'V','GTG':'V',
+                'GCT':'A','GCC':'A','GCA':'A','GCG':'A',
+                'GAT':'D','GAC':'D', 'GAA':'E','GAG':'E',
+                'GGT':'G','GGC':'G','GGA':'G','GGG':'G'}
+
+
+__complementTranslation = { "A": "T", "C": "G", "G": "C", "T": "A", "N": "N" }
+def complement(s):
+    """
+    Return complement of 's'.
+    """
+    c = "".join(__complementTranslation[n] for n in s)
+    return c
+
+
+def reverse(s):
+    """
+    Return reverse of 's'.
+    """
+    r = "".join(reversed(s))
+    return r
+
+
+def peptides(seq, start):
+    for i in range(start, len(seq), 3):
+        yield dna_to_aa.get(seq[i:i+3], "X")
+
+
+def translate(seq):
+    for i in range(3):
+        pep = peptides(seq, i)
+        yield "".join(pep)
+
+    revcomp = reverse(complement((seq)))
+    for i in range(3):
+        pep = peptides(revcomp, i)
+        yield "".join(pep)
+
+def kmers(seq, k):
+    for start in range(len(seq) - k + 1):
+        yield seq[start:start + k]
+
+###
+
+K = 21
+
+import sys, screed
+import mmh3
+import sourmash_lib
+print('imported sourmash:', sourmash_lib, file=sys.stderr)
+from sourmash_lib import MinHash
+import sourmash_lib.signature
+
+record = next(iter(screed.open(sys.argv[1])))
+print('loaded', record.name, file=sys.stderr)
+
+E = sourmash_lib.Estimators(ksize=K, n=500, protein=True)
+prot_ksize = int(K / 3)
+mh = E.mh
+
+for kmer in kmers(record.sequence, prot_ksize):
+    hash = mmh3.hash128(kmer, seed=42)
+    mh.add_hash(hash)
+
+s = sourmash_lib.signature.SourmashSignature('', E, name=record.name)
+print(sourmash_lib.signature.save_signatures([s]))
diff --git a/utils/compute-prot-mh-another-way.py b/utils/compute-prot-mh-another-way.py
new file mode 100755
index 000000000..b5f416e57
--- /dev/null
+++ b/utils/compute-prot-mh-another-way.py
@@ -0,0 +1,88 @@
+#! /usr/bin/env python
+"""
+Use the MurmurHash library mmh3 and separate Python code to calculate
+a MinHash signature for translated protein sequence, as a way to do an
+external check on our C++ implementation.
+
+The output of this is used in test_sourmash.py to verify our C++ code.
+"""
+
+dna_to_aa={'TTT':'F','TTC':'F', 'TTA':'L','TTG':'L',
+                'TCT':'S','TCC':'S','TCA':'S','TCG':'S',
+                'TAT':'Y','TAC':'Y', 'TAA':'*','TAG':'*','TGA':'*',
+                'TGT':'C','TGC':'C', 'TGG':'W',
+                'CTT':'L','CTC':'L','CTA':'L','CTG':'L',
+                'CCT':'P','CCC':'P','CCA':'P','CCG':'P',
+                'CAT':'H','CAC':'H', 'CAA':'Q','CAG':'Q',
+                'CGT':'R','CGC':'R','CGA':'R','CGG':'R',
+                'ATT':'I','ATC':'I','ATA':'I', 'ATG':'M',
+                'ACT':'T','ACC':'T','ACA':'T','ACG':'T',
+                'AAT':'N','AAC':'N', 'AAA':'K','AAG':'K',
+                'AGT':'S','AGC':'S', 'AGA':'R','AGG':'R',
+                'GTT':'V','GTC':'V','GTA':'V','GTG':'V',
+                'GCT':'A','GCC':'A','GCA':'A','GCG':'A',
+                'GAT':'D','GAC':'D', 'GAA':'E','GAG':'E',
+                'GGT':'G','GGC':'G','GGA':'G','GGG':'G'}
+
+
+__complementTranslation = { "A": "T", "C": "G", "G": "C", "T": "A", "N": "N" }
+def complement(s):
+    """
+    Return complement of 's'.
+    """
+    c = "".join(__complementTranslation[n] for n in s)
+    return c
+
+
+def reverse(s):
+    """
+    Return reverse of 's'.
+    """
+    r = "".join(reversed(s))
+    return r
+
+
+def peptides(seq, start):
+    for i in range(start, len(seq), 3):
+        yield dna_to_aa.get(seq[i:i+3], "X")
+
+
+def translate(seq):
+    for i in range(3):
+        pep = peptides(seq, i)
+        yield "".join(pep)
+
+    revcomp = reverse(complement((seq)))
+    for i in range(3):
+        pep = peptides(revcomp, i)
+        yield "".join(pep)
+
+def kmers(seq, k):
+    for start in range(len(seq) - k + 1):
+        yield seq[start:start + k]
+
+###
+
+K = 21
+
+import sys, screed
+import mmh3
+import sourmash_lib
+print('imported sourmash:', sourmash_lib, file=sys.stderr)
+from sourmash_lib import MinHash
+import sourmash_lib.signature
+
+record = next(iter(screed.open(sys.argv[1])))
+print('loaded', record.name, file=sys.stderr)
+
+E = sourmash_lib.Estimators(ksize=K, n=500, protein=True)
+prot_ksize = int(K / 3)
+mh = E.mh
+
+for trans in translate(record.sequence):
+    for kmer in kmers(trans, prot_ksize):
+        hash = mmh3.hash128(kmer, seed=42)
+        mh.add_hash(hash)
+
+s = sourmash_lib.signature.SourmashSignature('', E, name=record.name)
+print(sourmash_lib.signature.save_signatures([s]))