diff --git a/src/services/completions.ts b/src/services/completions.ts
index d86b094d3d..a6fd37fde6 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -1871,7 +1871,7 @@ namespace ts.Completions {
                 return contextualMemberSymbols;
             }
 
-            const membersDeclaredBySpreadAssignment = createMap<boolean>();
+            const membersDeclaredBySpreadAssignment = createMap<true>();
             const existingMemberNames = createUnderscoreEscapedMap<boolean>();
             for (const m of existingMembers) {
                 // Ignore omitted expressions for missing members
@@ -1918,7 +1918,7 @@ namespace ts.Completions {
             return filteredSymbols;
         }
 
-        function setMembersDeclaredBySpreadAssignment(declaration: SpreadAssignment | JsxSpreadAttribute, membersDeclaredBySpreadAssignment: Map<boolean>) {
+        function setMembersDeclaredBySpreadAssignment(declaration: SpreadAssignment | JsxSpreadAttribute, membersDeclaredBySpreadAssignment: Map<true>) {
             const expression = declaration.expression;
             const symbol = typeChecker.getSymbolAtLocation(expression);
             const type = symbol && typeChecker.getTypeOfSymbolAtLocation(symbol, expression);
@@ -1940,7 +1940,7 @@ namespace ts.Completions {
         }
 
         // Set SortText to MemberDeclaredBySpreadAssignment if it is fulfilled by spread assignment
-        function setSortTextToMemberDeclaredBySpreadAssignment(membersDeclaredBySpreadAssignment: Map<boolean>, contextualMemberSymbols: Symbol[]): void {
+        function setSortTextToMemberDeclaredBySpreadAssignment(membersDeclaredBySpreadAssignment: Map<true>, contextualMemberSymbols: Symbol[]): void {
             if (membersDeclaredBySpreadAssignment.size === 0) {
                 return;
             }
@@ -2002,7 +2002,7 @@ namespace ts.Completions {
          */
         function filterJsxAttributes(symbols: Symbol[], attributes: NodeArray<JsxAttribute | JsxSpreadAttribute>): Symbol[] {
             const seenNames = createUnderscoreEscapedMap<boolean>();
-            const membersDeclaredBySpreadAssignment = createMap<boolean>();
+            const membersDeclaredBySpreadAssignment = createMap<true>();
             for (const attr of attributes) {
                 // If this is the current item we are editing right now, do not filter it out
                 if (isCurrentlyEditingNode(attr)) {