diff --git a/core/bash_impl.py b/core/bash_impl.py
index cfc530baa4..78da8bf685 100644
--- a/core/bash_impl.py
+++ b/core/bash_impl.py
@@ -198,6 +198,12 @@ def BashAssoc_SetElement(assoc_val, key, s):
     assoc_val.d[key] = s
 
 
+def BashAssoc_UnsetElement(assoc_val, key):
+    # type: (value.BashAssoc, str) -> None
+
+    mylib.dict_erase(assoc_val.d, key)
+
+
 def BashAssoc_ToStrForShellPrint(assoc_val):
     # type: (value.BashAssoc) -> str
 
diff --git a/core/state.py b/core/state.py
index c17363cfc4..0ece2292ac 100644
--- a/core/state.py
+++ b/core/state.py
@@ -2302,7 +2302,7 @@ def Unset(self, lval, which_scopes):
                 #  raise error.Runtime("%r isn't an associative array" % lval.name)
 
                 val = cast(value.BashAssoc, UP_val)
-                mylib.dict_erase(val.d, lval.key)
+                bash_impl.BashAssoc_UnsetElement(val, lval.key)
 
             else:
                 raise AssertionError(lval)
diff --git a/spec/array.test.sh b/spec/array.test.sh
index 08f1784bff..6472798618 100644
--- a/spec/array.test.sh
+++ b/spec/array.test.sh
@@ -897,8 +897,8 @@ unset -v 'a[-2]'
 ## END
 ## STDERR:
   unset -v 'a[-2]'
-  ^~~~~
-[ stdin ]:4: fatal: Index -2 is out of bounds for array of length 1
+           ^
+[ stdin ]:4: a[-2]: Index is out of bounds for array of length 1
 ## END
 
 ## OK bash STDERR: