diff --git a/fsspec/mapping.py b/fsspec/mapping.py
index 17fe7ae79..235da8d24 100644
--- a/fsspec/mapping.py
+++ b/fsspec/mapping.py
@@ -88,6 +88,8 @@ def getitems(self, keys, on_error="raise"):
         oe = on_error if on_error == "raise" else "return"
         try:
             out = self.fs.cat(keys2, on_error=oe)
+            if isinstance(out, bytes):
+                out = {keys2[0]: out}
         except self.missing_exceptions as e:
             raise KeyError from e
         out = {