diff --git a/changelog.d/9985.misc b/changelog.d/9985.misc
new file mode 100644
index 000000000..97bd747f2
--- /dev/null
+++ b/changelog.d/9985.misc
@@ -0,0 +1 @@
+Simplify a few helper functions.
diff --git a/synapse/util/stringutils.py b/synapse/util/stringutils.py
index 40cd51a8c..f02943219 100644
--- a/synapse/util/stringutils.py
+++ b/synapse/util/stringutils.py
@@ -55,9 +55,7 @@ def random_string_with_symbols(length: int) -> str:
 def is_ascii(s: bytes) -> bool:
     try:
         s.decode("ascii").encode("ascii")
-    except UnicodeDecodeError:
-        return False
-    except UnicodeEncodeError:
+    except UnicodeError:
         return False
     return True