diff --git a/src/go/parser/parser.go b/src/go/parser/parser.go
index 41c3f2943e..5c4cea8638 100644
--- a/src/go/parser/parser.go
+++ b/src/go/parser/parser.go
@@ -1485,8 +1485,9 @@ func (p *parser) parseIndexOrSliceOrInstance(x ast.Expr) ast.Expr {
 		// empty index, slice or index expressions are not permitted;
 		// accept them for parsing tolerance, but complain
 		p.errorExpected(p.pos, "operand")
+		rbrack := p.pos
 		p.next()
-		return x
+		return &ast.BadExpr{From: x.Pos(), To: rbrack}
 	}
 	p.exprLev++
 
diff --git a/src/go/parser/testdata/issue44504.src b/src/go/parser/testdata/issue44504.src
new file mode 100644
index 0000000000..7791f4a809
--- /dev/null
+++ b/src/go/parser/testdata/issue44504.src
@@ -0,0 +1,13 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test case for issue 44504: panic due to duplicate resolution of slice/index
+// operands. We should not try to resolve a LHS expression with invalid syntax.
+
+package p
+
+func _() {
+  var items []bool
+  items[] /* ERROR "operand" */ = false
+}
diff --git a/src/go/types/fixedbugs/issue39634.go2 b/src/go/types/fixedbugs/issue39634.go2
index 249542d541..78dee00383 100644
--- a/src/go/types/fixedbugs/issue39634.go2
+++ b/src/go/types/fixedbugs/issue39634.go2
@@ -84,7 +84,7 @@ var x T25 /* ERROR without instantiation */ .m1
 
 // crash 26
 type T26 = interface{ F26[ /* ERROR methods cannot have type parameters */ Z any]() }
-func F26[Z any]() T26 { return F26 /* ERROR without instantiation */ /* ERROR missing method */ [] /* ERROR operand */ }
+func F26[Z any]() T26 { return F26[] /* ERROR operand */ }
 
 // crash 27
 func e27[T any]() interface{ x27 /* ERROR not a type */ }