diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index e47a28359d5..27e1b8117f4 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -4650,15 +4650,15 @@ namespace ts {
             let jsDocType: Type | undefined;
             for (const declaration of symbol.declarations) {
                 let declarationInConstructor = false;
-                const expression = declaration.kind === SyntaxKind.BinaryExpression ? <BinaryExpression>declaration :
-                    declaration.kind === SyntaxKind.PropertyAccessExpression ? cast(declaration.parent, isBinaryExpression) :
+                const expression = isBinaryExpression(declaration) ? declaration :
+                    isPropertyAccessExpression(declaration) ? isBinaryExpression(declaration.parent) ? declaration.parent : declaration :
                         undefined;
 
                 if (!expression) {
                     return errorType;
                 }
 
-                const special = getSpecialPropertyAssignmentKind(expression);
+                const special = isPropertyAccessExpression(expression) ? getSpecialPropertyAccessKind(expression) : getSpecialPropertyAssignmentKind(expression);
                 if (special === SpecialPropertyAssignmentKind.ThisProperty) {
                     const thisContainer = getThisContainer(expression, /*includeArrowFunctions*/ false);
                     // Properties defined in a constructor (or base constructor, or javascript constructor function) don't get undefined added.
@@ -4687,7 +4687,7 @@ namespace ts {
                         errorNextVariableOrPropertyDeclarationMustHaveSameType(jsDocType, declaration, declarationType);
                     }
                 }
-                else if (!jsDocType) {
+                else if (!jsDocType && isBinaryExpression(expression)) {
                     // If we don't have an explicit JSDoc type, get the type from the expression.
                     let type = getWidenedLiteralType(checkExpressionCached(expression.right));
 
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index c9278b55eda..9c933b44d01 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -1887,6 +1887,14 @@ namespace ts {
             return SpecialPropertyAssignmentKind.None;
         }
         const lhs = expr.left;
+        if (isEntityNameExpression(lhs.expression) && lhs.name.escapedText === "prototype" && isObjectLiteralExpression(getInitializerOfBinaryExpression(expr))) {
+                // F.prototype = { ... }
+                return SpecialPropertyAssignmentKind.Prototype;
+        }
+        return getSpecialPropertyAccessKind(lhs);
+    }
+
+    export function getSpecialPropertyAccessKind(lhs: PropertyAccessExpression): SpecialPropertyAssignmentKind {
         if (lhs.expression.kind === SyntaxKind.ThisKeyword) {
             return SpecialPropertyAssignmentKind.ThisProperty;
         }
@@ -1895,11 +1903,7 @@ namespace ts {
             return SpecialPropertyAssignmentKind.ModuleExports;
         }
         else if (isEntityNameExpression(lhs.expression)) {
-            if (lhs.name.escapedText === "prototype" && isObjectLiteralExpression(getInitializerOfBinaryExpression(expr))) {
-                // F.prototype = { ... }
-                return SpecialPropertyAssignmentKind.Prototype;
-            }
-            else if (isPrototypeAccess(lhs.expression)) {
+            if (isPrototypeAccess(lhs.expression)) {
                 // F.G....prototype.x = expr
                 return SpecialPropertyAssignmentKind.PrototypeProperty;
             }
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index 65fae36752b..489cf717c13 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -6262,6 +6262,7 @@ declare namespace ts {
     function isExportsIdentifier(node: Node): boolean;
     function isModuleExportsPropertyAccessExpression(node: Node): boolean;
     function getSpecialPropertyAssignmentKind(expr: BinaryExpression): SpecialPropertyAssignmentKind;
+    function getSpecialPropertyAccessKind(lhs: PropertyAccessExpression): SpecialPropertyAssignmentKind;
     function getInitializerOfBinaryExpression(expr: BinaryExpression): Expression;
     function isPrototypePropertyAssignment(node: Node): boolean;
     function isSpecialPropertyDeclaration(expr: PropertyAccessExpression): boolean;
diff --git a/tests/baselines/reference/jsdocPrototypePropertyAccessWithType.symbols b/tests/baselines/reference/jsdocPrototypePropertyAccessWithType.symbols
new file mode 100644
index 00000000000..00e906ea4ad
--- /dev/null
+++ b/tests/baselines/reference/jsdocPrototypePropertyAccessWithType.symbols
@@ -0,0 +1,16 @@
+=== /a.js ===
+function C() { this.x = false; };
+>C : Symbol(C, Decl(a.js, 0, 0))
+>x : Symbol(C.x, Decl(a.js, 0, 14), Decl(a.js, 0, 33))
+
+/** @type {number} */
+C.prototype.x;
+>C.prototype : Symbol(Function.prototype, Decl(lib.es5.d.ts, --, --))
+>C : Symbol(C, Decl(a.js, 0, 0))
+>prototype : Symbol(Function.prototype, Decl(lib.es5.d.ts, --, --))
+
+new C().x;
+>new C().x : Symbol(C.x, Decl(a.js, 0, 14), Decl(a.js, 0, 33))
+>C : Symbol(C, Decl(a.js, 0, 0))
+>x : Symbol(C.x, Decl(a.js, 0, 14), Decl(a.js, 0, 33))
+
diff --git a/tests/baselines/reference/jsdocPrototypePropertyAccessWithType.types b/tests/baselines/reference/jsdocPrototypePropertyAccessWithType.types
new file mode 100644
index 00000000000..6756c07f231
--- /dev/null
+++ b/tests/baselines/reference/jsdocPrototypePropertyAccessWithType.types
@@ -0,0 +1,23 @@
+=== /a.js ===
+function C() { this.x = false; };
+>C : typeof C
+>this.x = false : false
+>this.x : any
+>this : any
+>x : any
+>false : false
+
+/** @type {number} */
+C.prototype.x;
+>C.prototype.x : any
+>C.prototype : any
+>C : typeof C
+>prototype : any
+>x : any
+
+new C().x;
+>new C().x : number
+>new C() : C
+>C : typeof C
+>x : number
+
diff --git a/tests/cases/conformance/jsdoc/jsdocPrototypePropertyAccessWithType.ts b/tests/cases/conformance/jsdoc/jsdocPrototypePropertyAccessWithType.ts
new file mode 100644
index 00000000000..b9e3c2719be
--- /dev/null
+++ b/tests/cases/conformance/jsdoc/jsdocPrototypePropertyAccessWithType.ts
@@ -0,0 +1,9 @@
+// @allowJs: true
+// @checkJs: true
+// @noEmit: true
+
+// @Filename: /a.js
+function C() { this.x = false; };
+/** @type {number} */
+C.prototype.x;
+new C().x;