diff --git a/nominatim/db/sqlalchemy_functions.py b/nominatim/db/sqlalchemy_functions.py
index 5a0418b37..582dba2ff 100644
--- a/nominatim/db/sqlalchemy_functions.py
+++ b/nominatim/db/sqlalchemy_functions.py
@@ -216,7 +216,7 @@ class RegexpWord(sa.sql.functions.GenericFunction[Any]):
 @compiles(RegexpWord, 'postgresql') # type: ignore[no-untyped-call, misc]
 def postgres_regexp_nocase(element: RegexpWord, compiler: 'sa.Compiled', **kw: Any) -> str:
     arg1, arg2 = list(element.clauses)
-    return "regexp_like(%s, '\\m(' || %s  || ')\\M', 'i')" % (compiler.process(arg2, **kw), compiler.process(arg1, **kw))
+    return "regexp_like(%s, '\\m(' || %s  || ')\\M', 'i'::text)" % (compiler.process(arg2, **kw), compiler.process(arg1, **kw))
 
 @compiles(RegexpWord, 'sqlite') # type: ignore[no-untyped-call, misc]
 def sqlite_regexp_nocase(element: RegexpWord, compiler: 'sa.Compiled', **kw: Any) -> str: