diff --git a/arraycontext/impl/pytato.py b/arraycontext/impl/pytato.py
index 153ab14572dad39d6e5b1e266a2da49d04285399..d690570d86f42917b2e73a1c16e38796d091efd5 100644
--- a/arraycontext/impl/pytato.py
+++ b/arraycontext/impl/pytato.py
@@ -172,6 +172,23 @@ class ArrayContainerInputDescriptor(AbstractInputDescriptor):
                                                         Tuple[int, ...]]]"
 
 
+def _ary_container_key_stringifier(keys: Tuple[Any, ...]) -> str:
+    """
+    Helper for :meth:`PytatoCompiledOperator.__call__`. Stringifies an
+    array-container's component's key. The aim is that no-two different keys
+    have the same stringification.
+    """
+    def _rec_str(key: Any) -> str:
+        if isinstance(key, (str, int)):
+            return key
+        elif isinstance(key, tuple):
+            return "tup" + "_".join(_rec_str(k) for k in key) + "endtup"
+        else:
+            raise NotImplementedError
+
+    return "_".join(_rec_str(key) for key in keys)
+
+
 @dataclass
 class PytatoCompiledOperator:
     actx: ArrayContext
@@ -226,8 +243,8 @@ class PytatoCompiledOperator:
                 return pt.make_placeholder((), np.dtype(arg), name)
             elif is_array_container(arg):
                 def _rec_to_placeholder(keys, ary):
-                    name = f"_actx_in_{pos}_" + "_".join(str(key)
-                                                         for key in keys)
+                    name = (f"_actx_in_{pos}_"
+                            + _ary_container_key_stringifier(keys))
                     input_naming_map[(pos,) + keys] = name
                     return pt.make_placeholder(ary.shape, ary.dtype,
                                                name)