diff --git a/package-lock.json b/package-lock.json
index c7ea0b8..3157082 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
     "name": "@openwebwork/codemirror-lang-pg",
-    "version": "0.0.1-beta.19",
+    "version": "0.0.1-beta.20",
     "lockfileVersion": 3,
     "requires": true,
     "packages": {
         "": {
             "name": "@openwebwork/codemirror-lang-pg",
-            "version": "0.0.1-beta.19",
+            "version": "0.0.1-beta.20",
             "license": "MIT",
             "dependencies": {
                 "@codemirror/language": "^6.10.2",
diff --git a/package.json b/package.json
index 1ce59e3..d5cc388 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@openwebwork/codemirror-lang-pg",
-    "version": "0.0.1-beta.19",
+    "version": "0.0.1-beta.20",
     "description": "PG language support for CodeMirror",
     "author": "The WeBWorK Project",
     "license": "MIT",
diff --git a/src/pg.grammar b/src/pg.grammar
index 5426464..45460eb 100644
--- a/src/pg.grammar
+++ b/src/pg.grammar
@@ -123,17 +123,13 @@ expression[@isGroup=Expression] {
         (ScalarVariable | PGVariable | expression)
         !arrayMember
         (ArrowOperator !arrowOperator)?
-        "["
-        expression
-        "]"
+        arrayAccessor
     } |
     HashAccessVariable {
         (ScalarVariable | PGVariable | expression)
         !hashMember
         (ArrowOperator !arrowOperator)?
-        "{"
-        ((!bareword Identifier) | expression)
-        "}"
+        hashAccessor
     } |
     PatternMatchM |
     PatternMatch |
@@ -308,6 +304,9 @@ List { !list "(" !listContents commaSep<expression> ")" }
 ArrayRef { "[" commaSep<expression> "]" }
 HashRef { ArithOp<"+">? "{" commaSep<expression> "}" }
 
+arrayAccessor { "[" expression "]" }
+hashAccessor { "{" ((!bareword Identifier) | expression) "}" }
+
 ScalarDereference { "$" (ScalarDereference | ScalarVariable | PGVariable | "{" expression "}") }
 ArrayDereference { "@" (ScalarDereference | ScalarVariable | PGVariable | "{" expression "}") }
 HashDereference { "%" (ScalarDereference | ScalarVariable | PGVariable | "{" expression "}") }
@@ -430,18 +429,14 @@ semicolon { StatementEnd | automaticSemicolon }
         afterInterpolation?
         !arrayMember
         (ArrowOperator !arrowOperator)?
-        "["
-        maybeParens<ArithOp<"-">? Integer | Float | ScalarVariable | PGVariable | quotedString>
-        "]"
+        arrayAccessor
     }
     HashAccessVariable {
         (ScalarVariable | PGVariable | ArrayAccessVariable | HashAccessVariable)
         afterInterpolation?
         !hashMember
         (ArrowOperator !arrowOperator)?
-        "{"
-        (!bareword Identifier | maybeParens<ScalarVariable | PGVariable | quotedString>)
-        "}"
+        hashAccessor
     }
 
     PodStatement { PodDirective PodContent PodCut }
diff --git a/test/perl-heredocs.txt b/test/perl-heredocs.txt
index 8116996..11d0026 100644
--- a/test/perl-heredocs.txt
+++ b/test/perl-heredocs.txt
@@ -94,7 +94,7 @@ Program(
                 InterpolatedStringContent,
                 ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", Integer, "]"),
                 InterpolatedStringContent,
-                ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", ArithOp, Integer, "]"),
+                ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", UnaryExpression(ArithOp, Integer), "]"),
                 InterpolatedStringContent,
                 ArrayAccessVariable(
                     ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", Integer, "]"),
diff --git a/test/perl-quote-and-quote-like-operators.txt b/test/perl-quote-and-quote-like-operators.txt
index e0813b1..e4d9bfb 100644
--- a/test/perl-quote-and-quote-like-operators.txt
+++ b/test/perl-quote-and-quote-like-operators.txt
@@ -19,9 +19,9 @@ Program(
             InterpolatedStringContent,
             ArrayAccessVariable(ScalarVariable, "[", Integer, "]"),
             InterpolatedStringContent,
-            ArrayAccessVariable(ScalarVariable, "[", "(", ArithOp, Integer, ")", "]"),
+            ArrayAccessVariable(ScalarVariable, "[", List("(", UnaryExpression(ArithOp, Integer), ")"), "]"),
             InterpolatedStringContent,
-            ArrayAccessVariable(ScalarVariable, "[", "(", ScalarVariable, ")", "]"),
+            ArrayAccessVariable(ScalarVariable, "[", List("(", ScalarVariable, ")"), "]"),
             InterpolatedStringContent,
             ArrayAccessVariable(ScalarVariable, "[", ScalarVariable, "]")
         ),
@@ -32,7 +32,13 @@ Program(
             InterpolatedStringContent,
             ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", Integer, "]"),
             InterpolatedStringContent,
-            ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", "(", ArithOp, Integer, ")", "]"),
+            ArrayAccessVariable(
+                ScalarVariable,
+                ArrowOperator,
+                "[",
+                List("(", UnaryExpression(ArithOp, Integer), ")"),
+                "]"
+            ),
             InterpolatedStringContent,
             ArrayAccessVariable(
                 ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", Integer, "]"),
@@ -51,7 +57,7 @@ Program(
             InterpolatedStringContent,
             ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", ScalarVariable, "]"),
             InterpolatedStringContent,
-            ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", "(", ScalarVariable, ")", "]")
+            ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", List("(", ScalarVariable, ")"), "]")
         ),
         StatementEnd(";")
     ),
@@ -62,9 +68,9 @@ Program(
             InterpolatedStringContent,
             HashAccessVariable(ScalarVariable, "{", ScalarVariable, "}"),
             InterpolatedStringContent,
-            HashAccessVariable(ScalarVariable, "{", "(", StringSingleQuoted, ")", "}"),
+            HashAccessVariable(ScalarVariable, "{", List("(", StringSingleQuoted, ")"), "}"),
             InterpolatedStringContent,
-            HashAccessVariable(ScalarVariable, "{", "(", ScalarVariable, ")", "}")
+            HashAccessVariable(ScalarVariable, "{", List("(", ScalarVariable, ")"), "}")
         ),
         StatementEnd(";")
     ),
@@ -90,9 +96,9 @@ Program(
             InterpolatedStringContent,
             HashAccessVariable(ScalarVariable, ArrowOperator, "{", ScalarVariable, "}"),
             InterpolatedStringContent,
-            HashAccessVariable(ScalarVariable, ArrowOperator, "{", "(", StringSingleQuoted, ")", "}"),
+            HashAccessVariable(ScalarVariable, ArrowOperator, "{", List("(", StringSingleQuoted, ")"), "}"),
             InterpolatedStringContent,
-            HashAccessVariable(ScalarVariable, ArrowOperator, "{", "(", ScalarVariable, ")", "}")
+            HashAccessVariable(ScalarVariable, ArrowOperator, "{", List("(", ScalarVariable, ")"), "}")
         ),
         StatementEnd(";")
     ),
@@ -243,7 +249,7 @@ Program(
             qq,
             QuoteLikeStartDelimiter,
             InterpolatedStringContent,
-            ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", ArithOp, Integer, "]"),
+            ArrayAccessVariable(ScalarVariable, ArrowOperator, "[", UnaryExpression(ArithOp, Integer), "]"),
             QuoteLikeEndDelimiter
         ),
         StatementEnd(";")