diff --git a/osh/expr_eval.py b/osh/expr_eval.py
index f0f83a1a57..6eba994b6e 100755
--- a/osh/expr_eval.py
+++ b/osh/expr_eval.py
@@ -438,13 +438,21 @@ def Eval(self, node, int_coerce=True):
 
       rhs = self.Eval(node.right)  # eager evaluation for the rest
 
+      # TODO: Validate that in lhs + rhs, both are STRINGS and not [] or {}.
+
       if op_id == Id.Arith_LBracket:
-        if not isinstance(lhs, list):
+        # StrArray or AssocArray
+        if not isinstance(lhs, (list, dict)):
           # TODO: Add error context
           e_die('Expected array in index expression, got %s', lhs)
 
         try:
           item = lhs[rhs]
+        except KeyError:
+          if self.exec_opts.nounset:
+            e_die('Invalid key %r' % rhs)
+          else:
+            return 0  # If not fatal, return 0
         except IndexError:
           if self.exec_opts.nounset:
             e_die('Index out of bounds')
diff --git a/osh/runtime.asdl b/osh/runtime.asdl
index c2fe746ec5..10272c437c 100644
--- a/osh/runtime.asdl
+++ b/osh/runtime.asdl
@@ -41,7 +41,7 @@ module runtime
   -- TODO:
   -- * add spid for last-assigned location
   -- * use a bitfield for flags.
-  cell = (value val, bool exported, bool readonly, bool is_assoc_array)
+  cell = (value val, bool exported, bool readonly)
 
   -- An undefined variable can become an indexed array with s[x]=1.  But if we
   -- 'declare -A' it, it will be undefined and waiting to turn into an
diff --git a/osh/state.py b/osh/state.py
index e380a213b3..7066d54244 100644
--- a/osh/state.py
+++ b/osh/state.py
@@ -857,8 +857,6 @@ def IsAssocArray(self, name, lookup_mode):
     if cell:
       if cell.val.tag == value_e.AssocArray:  # foo=([key]=value)
         return True
-      if cell.is_assoc_array:  # declare -A
-        return True
     return False
 
   def SetVar(self, lval, val, new_flags, lookup_mode):
@@ -922,10 +920,6 @@ def SetVar(self, lval, val, new_flags, lookup_mode):
           cell.exported = True
         if var_flags_e.ReadOnly in new_flags:
           cell.readonly = True
-        if var_flags_e.AssocArray in new_flags:
-          # doesn't do anything
-          #cell.is_assoc_array = True
-          pass
       else:
         if val is None:
           # set -o nounset; local foo; echo $foo  # It's still undefined!
@@ -936,9 +930,7 @@ def SetVar(self, lval, val, new_flags, lookup_mode):
 
         cell = runtime_asdl.cell(val,
                                  var_flags_e.Exported in new_flags,
-                                 var_flags_e.ReadOnly in new_flags,
-                                 #var_flags_e.AssocArray in new_flags)
-                                 False)
+                                 var_flags_e.ReadOnly in new_flags)
         namespace[lval.name] = cell
 
       if (cell.val is not None and
@@ -977,13 +969,9 @@ def SetVar(self, lval, val, new_flags, lookup_mode):
       if cell.readonly:
         e_die("Can't assign to readonly value", span_id=left_spid)
 
-      # This is for the case where we did declare -a foo or declare -A foo.
-      # There IS a cell, but it's still undefined.
+      # undef[0]=y is allowed
       if cell_tag == value_e.Undef:
-        if cell.is_assoc_array:
-          self._BindNewAssocArrayWithEntry(namespace, lval, val, new_flags)
-        else:
-          self._BindNewArrayWithEntry(namespace, lval, val, new_flags)
+        self._BindNewArrayWithEntry(namespace, lval, val, new_flags)
         return
 
       if cell_tag == value_e.StrArray:
@@ -1016,7 +1004,7 @@ def _BindNewArrayWithEntry(self, namespace, lval, val, new_flags):
 
     # arrays can't be exported; can't have AssocArray flag
     readonly = var_flags_e.ReadOnly in new_flags
-    namespace[lval.name] = runtime_asdl.cell(new_value, False, readonly, False)
+    namespace[lval.name] = runtime_asdl.cell(new_value, False, readonly)
 
   def _BindNewAssocArrayWithEntry(self, namespace, lval, val, new_flags):
     """Fill 'namespace' with a new indexed array entry."""
@@ -1025,7 +1013,7 @@ def _BindNewAssocArrayWithEntry(self, namespace, lval, val, new_flags):
 
     # associative arrays can't be exported; don't need AssocArray flag
     readonly = var_flags_e.ReadOnly in new_flags
-    namespace[lval.name] = runtime_asdl.cell(new_value, False, readonly, False)
+    namespace[lval.name] = runtime_asdl.cell(new_value, False, readonly)
 
   def InternalSetGlobal(self, name, new_val):
     """For setting read-only globals internally.
diff --git a/osh/word_eval.py b/osh/word_eval.py
index 7fd387df30..c0edb3e1c2 100644
--- a/osh/word_eval.py
+++ b/osh/word_eval.py
@@ -425,6 +425,12 @@ def _ApplyPrefixOp(self, val, op_id, token):
         # There can be empty placeholder values in the array.
         length = sum(1 for s in val.strs if s is not None)
 
+      elif val.tag == value_e.AssocArray:
+        length = len(val.d)
+
+      else:
+        raise AssertionError(val.__class__.__name__)
+
       return value.Str(str(length))
 
     elif op_id == Id.VSub_Bang:  # ${!foo}, "indirect expansion"
diff --git a/spec/assign-extended.test.sh b/spec/assign-extended.test.sh
index a689392a3c..c481840cdc 100644
--- a/spec/assign-extended.test.sh
+++ b/spec/assign-extended.test.sh
@@ -276,9 +276,10 @@ argv.py "${ev["ev1"]}"
 
 #### myvar=typeset (another form of dynamic assignment)
 myvar=typeset
-$myvar x=42
+x='a b'
+$myvar x=$x
 echo $x
 ## STDOUT:
-42
+a
 ## END
 
diff --git a/spec/assoc.test.sh b/spec/assoc.test.sh
index 13df1ebc61..02aa5ed401 100644
--- a/spec/assoc.test.sh
+++ b/spec/assoc.test.sh
@@ -14,9 +14,17 @@
 # http://www.gnu.org/software/bash/manual/html_node/Arrays.html
 # TODO: Need a SETUP section.
 
-#### TODO: SETUP should be share
+#### Literal syntax ([x]=y)
 declare -A a
 a=([aa]=b [foo]=bar ['a+1']=c)
+echo ${a["aa"]}
+echo ${a["foo"]}
+echo ${a["a+1"]}
+## STDOUT:
+b
+bar
+c
+## END
 
 #### create empty assoc array, put, then get
 declare -A d  # still undefined
@@ -26,7 +34,6 @@ echo ${d['foo']}
 
 #### retrieve indices with !
 declare -A a
-#a=([aa]=b [foo]=bar ['a+1']=c)
 var='x'
 a["$var"]=b
 a['foo']=bar
@@ -48,55 +55,79 @@ echo "${a}"
 ## OK osh stdout-json: ""
 ## OK osh status: 1
 
-#### length of dict does not work
+#### length ${#a[@]}
 declare -A a
-a=([aa]=b [foo]=bar ['a+1']=c)
-echo "${#a}"
-## stdout: 0
+a["x"]=1
+a["y"]=2
+a["z"]=3
+echo "${#a[@]}"
+## stdout: 3
 
-#### index by number doesn't work
+#### retrieve values with numeric keys
 declare -A a
-a=([aa]=b [foo]=bar ['a+1']=c)
+a["0"]=a
+a["1"]=b
+a["2"]=c
 echo 0 "${a[0]}" 1 "${a[1]}" 2 "${a[2]}"
-## stdout-json: "0  1  2 \n"
+## STDOUT:
+0 a 1 b 2 c
+## END
 
-#### index by key name
+#### retrieve values with string keys
 declare -A a
-a=([aa]=b [foo]=bar ['a+1']=c)
-echo "${a[aa]}" "${a[foo]}" "${a['a+1']}"
-# WTF: Why do we get bar bar c?
-## stdout-json: "b bar c\n"
+a["aa"]=b
+a["foo"]=bar
+a['a+1']=c
+echo "${a["aa"]}" "${a["foo"]}" "${a["a+1"]}"
+## STDOUT:
+b bar c
+## END
 
-#### index by quoted string
+#### retrieve value with single quoted string
 declare -A a
-a=([aa]=b [foo]=bar ['a+1']=c)
+a["aa"]=b
+a["foo"]=bar
+a['a+1']=c
 echo "${a['a+1']}"
 ## stdout: c
 
-#### index by unquoted string
+#### index by unquoted string doesn't work in OSH because it's a variable
 declare -A a
-a=([aa]=b [foo]=bar ['a+1']=c)
+a["aa"]=b
+a["foo"]=bar
+a['a+1']=c
 echo "${a[a+1]}"
 ## stdout: c
 
 #### index by unquoted string as arithmetic
-# For assoc arrays, unquoted string is just raw.
-# For regular arrays, unquoted string is an arithmetic expression!
-# How do I parse this?
-declare -A assoc
-assoc=([a+1]=c)
+
+i=1
 array=(5 6 7)
-a=1
-echo "${assoc[a]}" 
-echo "${assoc[a+1]}"  # This works
-echo "${array[a+1]}"
-## stdout-json: "\nc\n7\n"
+echo array[i]="${array[i]}"
+echo array[i+1]="${array[i+1]}"
 
-#### WTF index by key name
-declare -A a
-a=([xx]=bb [cc]=dd)
-echo "${a[xx]}" "${a[cc]}"
-## stdout-json: "bb dd\n"
+# arithmetic does NOT work here in bash.  These are unquoted strings!
+declare -A assoc
+assoc[i]=$i
+assoc[i+1]=$i+1
+
+assoc["i"]=string
+assoc["i+1"]=string+1
+
+echo assoc[i]="${assoc[i]}" 
+echo assoc[i+1]="${assoc[i+1]}"
+
+echo assoc[i]="${assoc["i"]}" 
+echo assoc[i+1]="${assoc["i+1"]}"
+
+## STDOUT:
+array[i]=6
+array[i+1]=7
+assoc[i]=string
+assoc[i+1]=string+1
+assoc[i]=string
+assoc[i+1]=string+1
+## END
 
 #### Array stored in associative array gets converted to string
 array=('1 2' 3)
@@ -201,3 +232,15 @@ echo ${assoc[1]} ${assoc[2]} ${assoc}
 1 2 1 zero 2
 ## END
 ## N-I osh status: 1
+
+#### Associative array expressions inside (( ))
+declare -A assoc
+assoc[0]=42
+(( var = ${assoc[0]} ))
+echo $var
+(( var = assoc[0] ))
+echo $var
+## STDOUT:
+42
+42
+## END
diff --git a/spec/osh-only.test.sh b/spec/osh-only.test.sh
index 1b013990e7..0e143f1bf8 100644
--- a/spec/osh-only.test.sh
+++ b/spec/osh-only.test.sh
@@ -12,7 +12,7 @@ echo status=$?
 repr nonexistent
 echo status=$?
 ## STDOUT:
-x = (cell val:(value.Str s:42) exported:F readonly:F is_assoc_array:F)
+x = (cell val:(value.Str s:42) exported:F readonly:F)
 status=0
 'nonexistent' is not defined
 status=1
diff --git a/test/spec.sh b/test/spec.sh
index 352ebfb51e..340d054451 100755
--- a/test/spec.sh
+++ b/test/spec.sh
@@ -569,7 +569,7 @@ append() {
 
 # associative array -- mksh and zsh implement different associative arrays.
 assoc() {
-  sh-spec spec/assoc.test.sh --osh-failures-allowed 12 \
+  sh-spec spec/assoc.test.sh --osh-failures-allowed 9 \
     $BASH $OSH_LIST "$@"
 }