diff --git a/swh/model/hypothesis_strategies.py b/swh/model/hypothesis_strategies.py
--- a/swh/model/hypothesis_strategies.py
+++ b/swh/model/hypothesis_strategies.py
@@ -54,21 +54,17 @@
 )
 from .swhids import ExtendedObjectType, ExtendedSWHID
 
-
-def pgsql_alphabet(blacklist_chars=[]):
-    pgsql_blacklist_chars = ["\u0000"]  # postgresql does not like these
-    return characters(
-        blacklist_categories=("Cs",),
-        blacklist_characters=pgsql_blacklist_chars + blacklist_chars,
-    )
+pgsql_alphabet = characters(
+    blacklist_categories=("Cs",), blacklist_characters=["\u0000"]
+)  # postgresql does not like these
 
 
 def optional(strategy):
     return one_of(none(), strategy)
 
 
-def pgsql_text(blacklist_chars=[]):
-    return text(alphabet=pgsql_alphabet(blacklist_chars))
+def pgsql_text():
+    return text(alphabet=pgsql_alphabet)
 
 
 def sha1_git():
@@ -278,7 +274,7 @@
 def directory_entries_d():
     return builds(
         dict,
-        name=pgsql_text(blacklist_chars=["/"]).map(str.encode),
+        name=binary(),
         target=sha1_git(),
         type=sampled_from(["file", "dir", "rev"]),
         perms=sampled_from([perm.value for perm in DentryPerms]),