diff --git a/utils/mash-to-sourmash-sig.py b/utils/mash-to-sourmash-sig.py
new file mode 100755
index 0000000000..7df27d40ce
--- /dev/null
+++ b/utils/mash-to-sourmash-sig.py
@@ -0,0 +1,27 @@
+#! /usr/bin/env python
+import sys
+import json
+import sourmash_lib, sourmash_lib.signature
+
+x = json.loads(open(sys.argv[1]).read())
+ksize = x['kmer']
+num = x['sketchSize']
+
+assert x['hashType'] == "MurmurHash3_x64_128"
+assert x['hashBits'] == 64
+assert x['hashSeed'] == 42
+
+xx = x['sketches'][0]
+hashes = xx['hashes']
+
+# assert stuff HERE
+
+
+E = sourmash_lib.Estimators(ksize=ksize, n=num, is_protein=False)
+mh = E.mh
+for h in hashes:
+    mh.add_hash(h)
+
+s = sourmash_lib.signature.SourmashSignature('', E, name=sys.argv[1])
+print(sourmash_lib.signature.save_signatures([s]))
+