diff --git a/src/entry.py b/src/entry.py
index 9305ac5..81fcec2 100644
--- a/src/entry.py
+++ b/src/entry.py
@@ -7,6 +7,27 @@ Entry = namedtuple('Entry', ['salt', 'hashed_host', 'fingerprint', 'comment'])
 
 class UnacceptableComment(Exception): pass
 
+def normalize_host(domain, port):
+	"""normalize_host(str, u16) → bytes
+	Tranform a domain into the format in which it will be hashed"""
+	assert type(domain) == str
+	assert type(port) == int and 0 <= port <= (1<<16) - 1
+
+	# We want to have domain names reasonably normalized. This is why we
+	# convert all internationalized domain names to punycode and
+	# lowercase all domains.
+	# The reason the lowercasing happens after the punycoding is because
+	# that way we don't have to worry about Unicode case mapping: in
+	# case of IDN the IDNA codec handles that for us, and in case of an
+	# ASCII domain it passes through the IDNA unmodified
+	normalized_host = domain.encode('idna').lower()
+
+	# If the port is not :22, we store [host]:port instead
+	if port != 22:
+		normalized_host = b'[%s]:%i' % (normalized_host, port)
+
+	return normalized_host
+
 def create_entry(domain, port, fingerprint, comment):
 	"""create_entry(str, u16, bytes[32], str) → Entry
 	Given unprocessed host, a binary fingerprint and a comment, creates
@@ -16,21 +37,11 @@ def create_entry(domain, port, fingerprint, comment):
 	assert type(fingerprint) == bytes and len(fingerprint) == 32
 	assert type(comment) == str
 
-	# We want to have domain names reasonably normalized. This is why we
-	# convert all internationalized domain names to punycode and
-	# lowercase all domains.
-	# The reason the lowercasing happens after the punycoding is because
-	# that way we don't have to worry about Unicode case mapping: in
-	# case of IDN the IDNA codec handles that for us, and in case of an
-	# ASCII domain it passes through the IDNA unmodified
-	processed_host = domain.encode('idna').lower()
-
-	# If the port is not :22, we store [host]:port instead
-	if port != 22:
-		processed_host = b'[%s]%i' % (processed_host, port)
+	# Normalize the host before hashing
+	normalized_host = normalize_host(domain, port)
 
 	# Hash the host and store the salt
-	salt, hashed_host = hashing.hash_host(processed_host)
+	salt, hashed_host = hashing.hash_host(normalized_host)
 
 	# Comment must not include newlines
 	if '\n' in comment: