diff --git a/js/src/frontend/Parser.cpp b/js/src/frontend/Parser.cpp
index 33ff144af17c..8da9dd738d3f 100644
--- a/js/src/frontend/Parser.cpp
+++ b/js/src/frontend/Parser.cpp
@@ -4027,19 +4027,6 @@ Parser<ParseHandler>::PossibleError::transferErrorsTo(PossibleError* other)
     transferErrorTo(ErrorKind::Expression, other);
 }
 
-template <typename ParseHandler>
-bool
-Parser<ParseHandler>::checkAssignmentToCall(Node target, unsigned msg)
-{
-    MOZ_ASSERT(handler.isFunctionCall(target));
-
-    // Assignment to function calls is forbidden in ES6.  We're still somewhat
-    // concerned about sites using this in dead code, so forbid it only in
-    // strict mode code (or if the werror option has been set), and otherwise
-    // warn.
-    return reportWithNode(ParseStrictError, pc->sc()->strict(), target, msg);
-}
-
 template <>
 bool
 Parser<FullParseHandler>::checkDestructuringName(ParseNode* expr, Maybe<DeclarationKind> maybeDecl)
@@ -7867,7 +7854,11 @@ Parser<ParseHandler>::checkAndMarkAsIncOperand(Node target, AssignmentFlavor fla
         if (!reportIfArgumentsEvalTarget(target))
             return false;
     } else if (handler.isFunctionCall(target)) {
-        if (!checkAssignmentToCall(target, JSMSG_BAD_INCOP_OPERAND))
+        // Assignment to function calls is forbidden in ES6.  We're still
+        // somewhat concerned about sites using this in dead code, so forbid it
+        // only in strict mode code (or if the werror option has been set), and
+        // otherwise warn.
+        if (!reportWithNode(ParseStrictError, pc->sc()->strict(), target, JSMSG_BAD_INCOP_OPERAND))
             return false;
     }
     return true;
diff --git a/js/src/frontend/Parser.h b/js/src/frontend/Parser.h
index daf5f18c1f28..a4c13a02b0dc 100644
--- a/js/src/frontend/Parser.h
+++ b/js/src/frontend/Parser.h
@@ -1428,8 +1428,6 @@ class Parser final : private JS::AutoGCRooter, public StrictModeGetter
     bool checkDestructuringObject(Node objectPattern, const mozilla::Maybe<DeclarationKind>& maybeDecl);
     bool checkDestructuringName(Node expr, mozilla::Maybe<DeclarationKind> maybeDecl);
 
-    bool checkAssignmentToCall(Node node, unsigned errnum);
-
     Node newNumber(const Token& tok) {
         return handler.newNumber(tok.number(), tok.decimalPoint(), tok.pos);
     }