diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index ef11dc904ea19..06ef246340252 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -7662,7 +7662,7 @@ namespace ts {
 
         function getFlowTypeOfReference(reference: Node, declaredType: Type, assumeInitialized: boolean, includeOuterFunctions: boolean) {
             let key: string;
-            if (!reference.flowNode || assumeInitialized && (declaredType.flags & TypeFlags.NotNarrowable)) {
+            if (!reference.flowNode || assumeInitialized && !(declaredType.flags & TypeFlags.Narrowable)) {
                 return declaredType;
             }
             const initialType = assumeInitialized ? declaredType : addNullableKind(declaredType, TypeFlags.Undefined);
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 026ee5da9604e..c7e14a1003108 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -2218,13 +2218,7 @@ namespace ts {
         ObjectType = Class | Interface | Reference | Tuple | Anonymous,
         UnionOrIntersection = Union | Intersection,
         StructuredType = ObjectType | Union | Intersection,
-
-        // 'NotNarrowable' types are types where narrowing reverts to the original type, rather than actually narrow.
-        // This is never really correct - you can _always_ narrow to an intersection with that type, _but_ we keep
-        // Void as the only non-narrowable type, since it's a non-value type construct (representing a lack of a value)
-        // and, generally speaking, narrowing `void` should fail in some way, as it is nonsensical. (`void` narrowing
-        // to `void & T`, in a structural sense, is just narrowing to T, which we wouldn't allow under normal rules)
-        NotNarrowable = Void,
+        Narrowable = Any | ObjectType | Union | TypeParameter,
         /* @internal */
         RequiresWidening = ContainsUndefinedOrNull | ContainsObjectLiteral,
         /* @internal */
diff --git a/tests/baselines/reference/typeGuardNarrowsPrimitiveIntersection.js b/tests/baselines/reference/typeGuardNarrowsPrimitiveIntersection.js
deleted file mode 100644
index a4cba6f4ab5c1..0000000000000
--- a/tests/baselines/reference/typeGuardNarrowsPrimitiveIntersection.js
+++ /dev/null
@@ -1,38 +0,0 @@
-//// [typeGuardNarrowsPrimitiveIntersection.ts]
-type Tag = {__tag: any};
-declare function isNonBlank(value: string) : value is (string & Tag);
-declare function doThis(value: string & Tag): void;
-declare function doThat(value: string) : void;
-let value: string;
-if (isNonBlank(value)) {
-    doThis(value);
-} else {
-    doThat(value);
-}
-
-
-const enum Tag2 {}
-declare function isNonBlank2(value: string) : value is (string & Tag2);
-declare function doThis2(value: string & Tag2): void;
-declare function doThat2(value: string) : void;
-if (isNonBlank2(value)) {
-    doThis2(value);
-} else {
-    doThat2(value);
-}
-
-
-//// [typeGuardNarrowsPrimitiveIntersection.js]
-var value;
-if (isNonBlank(value)) {
-    doThis(value);
-}
-else {
-    doThat(value);
-}
-if (isNonBlank2(value)) {
-    doThis2(value);
-}
-else {
-    doThat2(value);
-}
diff --git a/tests/baselines/reference/typeGuardNarrowsPrimitiveIntersection.symbols b/tests/baselines/reference/typeGuardNarrowsPrimitiveIntersection.symbols
deleted file mode 100644
index da507fb94c5dc..0000000000000
--- a/tests/baselines/reference/typeGuardNarrowsPrimitiveIntersection.symbols
+++ /dev/null
@@ -1,70 +0,0 @@
-=== tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsPrimitiveIntersection.ts ===
-type Tag = {__tag: any};
->Tag : Symbol(Tag, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 0, 0))
->__tag : Symbol(__tag, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 0, 12))
-
-declare function isNonBlank(value: string) : value is (string & Tag);
->isNonBlank : Symbol(isNonBlank, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 0, 24))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 1, 28))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 1, 28))
->Tag : Symbol(Tag, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 0, 0))
-
-declare function doThis(value: string & Tag): void;
->doThis : Symbol(doThis, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 1, 69))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 2, 24))
->Tag : Symbol(Tag, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 0, 0))
-
-declare function doThat(value: string) : void;
->doThat : Symbol(doThat, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 2, 51))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 3, 24))
-
-let value: string;
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 4, 3))
-
-if (isNonBlank(value)) {
->isNonBlank : Symbol(isNonBlank, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 0, 24))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 4, 3))
-
-    doThis(value);
->doThis : Symbol(doThis, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 1, 69))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 4, 3))
-
-} else {
-    doThat(value);
->doThat : Symbol(doThat, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 2, 51))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 4, 3))
-}
-
-
-const enum Tag2 {}
->Tag2 : Symbol(Tag2, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 9, 1))
-
-declare function isNonBlank2(value: string) : value is (string & Tag2);
->isNonBlank2 : Symbol(isNonBlank2, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 12, 18))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 13, 29))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 13, 29))
->Tag2 : Symbol(Tag2, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 9, 1))
-
-declare function doThis2(value: string & Tag2): void;
->doThis2 : Symbol(doThis2, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 13, 71))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 14, 25))
->Tag2 : Symbol(Tag2, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 9, 1))
-
-declare function doThat2(value: string) : void;
->doThat2 : Symbol(doThat2, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 14, 53))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 15, 25))
-
-if (isNonBlank2(value)) {
->isNonBlank2 : Symbol(isNonBlank2, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 12, 18))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 4, 3))
-
-    doThis2(value);
->doThis2 : Symbol(doThis2, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 13, 71))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 4, 3))
-
-} else {
-    doThat2(value);
->doThat2 : Symbol(doThat2, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 14, 53))
->value : Symbol(value, Decl(typeGuardNarrowsPrimitiveIntersection.ts, 4, 3))
-}
-
diff --git a/tests/baselines/reference/typeGuardNarrowsPrimitiveIntersection.types b/tests/baselines/reference/typeGuardNarrowsPrimitiveIntersection.types
deleted file mode 100644
index 478363669b461..0000000000000
--- a/tests/baselines/reference/typeGuardNarrowsPrimitiveIntersection.types
+++ /dev/null
@@ -1,76 +0,0 @@
-=== tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsPrimitiveIntersection.ts ===
-type Tag = {__tag: any};
->Tag : { __tag: any; }
->__tag : any
-
-declare function isNonBlank(value: string) : value is (string & Tag);
->isNonBlank : (value: string) => value is string & { __tag: any; }
->value : string
->value : any
->Tag : { __tag: any; }
-
-declare function doThis(value: string & Tag): void;
->doThis : (value: string & { __tag: any; }) => void
->value : string & { __tag: any; }
->Tag : { __tag: any; }
-
-declare function doThat(value: string) : void;
->doThat : (value: string) => void
->value : string
-
-let value: string;
->value : string
-
-if (isNonBlank(value)) {
->isNonBlank(value) : boolean
->isNonBlank : (value: string) => value is string & { __tag: any; }
->value : string
-
-    doThis(value);
->doThis(value) : void
->doThis : (value: string & { __tag: any; }) => void
->value : string & { __tag: any; }
-
-} else {
-    doThat(value);
->doThat(value) : void
->doThat : (value: string) => void
->value : string
-}
-
-
-const enum Tag2 {}
->Tag2 : Tag2
-
-declare function isNonBlank2(value: string) : value is (string & Tag2);
->isNonBlank2 : (value: string) => value is string & Tag2
->value : string
->value : any
->Tag2 : Tag2
-
-declare function doThis2(value: string & Tag2): void;
->doThis2 : (value: string & Tag2) => void
->value : string & Tag2
->Tag2 : Tag2
-
-declare function doThat2(value: string) : void;
->doThat2 : (value: string) => void
->value : string
-
-if (isNonBlank2(value)) {
->isNonBlank2(value) : boolean
->isNonBlank2 : (value: string) => value is string & Tag2
->value : string
-
-    doThis2(value);
->doThis2(value) : void
->doThis2 : (value: string & Tag2) => void
->value : string & Tag2
-
-} else {
-    doThat2(value);
->doThat2(value) : void
->doThat2 : (value: string) => void
->value : string
-}
-
diff --git a/tests/baselines/reference/typeGuardNarrowsToLiteralType.js b/tests/baselines/reference/typeGuardNarrowsToLiteralType.js
deleted file mode 100644
index fdd2ee3fb7f75..0000000000000
--- a/tests/baselines/reference/typeGuardNarrowsToLiteralType.js
+++ /dev/null
@@ -1,21 +0,0 @@
-//// [typeGuardNarrowsToLiteralType.ts]
-declare function isFoo(value: string) : value is "foo";
-declare function doThis(value: "foo"): void;
-declare function doThat(value: string) : void;
-let value: string;
-if (isFoo(value)) {
-    doThis(value);
-} else {
-    doThat(value);
-}
-
-
-
-//// [typeGuardNarrowsToLiteralType.js]
-var value;
-if (isFoo(value)) {
-    doThis(value);
-}
-else {
-    doThat(value);
-}
diff --git a/tests/baselines/reference/typeGuardNarrowsToLiteralType.symbols b/tests/baselines/reference/typeGuardNarrowsToLiteralType.symbols
deleted file mode 100644
index 0d0ddc5f00dc1..0000000000000
--- a/tests/baselines/reference/typeGuardNarrowsToLiteralType.symbols
+++ /dev/null
@@ -1,32 +0,0 @@
-=== tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsToLiteralType.ts ===
-declare function isFoo(value: string) : value is "foo";
->isFoo : Symbol(isFoo, Decl(typeGuardNarrowsToLiteralType.ts, 0, 0))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralType.ts, 0, 23))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralType.ts, 0, 23))
-
-declare function doThis(value: "foo"): void;
->doThis : Symbol(doThis, Decl(typeGuardNarrowsToLiteralType.ts, 0, 55))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralType.ts, 1, 24))
-
-declare function doThat(value: string) : void;
->doThat : Symbol(doThat, Decl(typeGuardNarrowsToLiteralType.ts, 1, 44))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralType.ts, 2, 24))
-
-let value: string;
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralType.ts, 3, 3))
-
-if (isFoo(value)) {
->isFoo : Symbol(isFoo, Decl(typeGuardNarrowsToLiteralType.ts, 0, 0))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralType.ts, 3, 3))
-
-    doThis(value);
->doThis : Symbol(doThis, Decl(typeGuardNarrowsToLiteralType.ts, 0, 55))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralType.ts, 3, 3))
-
-} else {
-    doThat(value);
->doThat : Symbol(doThat, Decl(typeGuardNarrowsToLiteralType.ts, 1, 44))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralType.ts, 3, 3))
-}
-
-
diff --git a/tests/baselines/reference/typeGuardNarrowsToLiteralType.types b/tests/baselines/reference/typeGuardNarrowsToLiteralType.types
deleted file mode 100644
index 9835206deb9f4..0000000000000
--- a/tests/baselines/reference/typeGuardNarrowsToLiteralType.types
+++ /dev/null
@@ -1,35 +0,0 @@
-=== tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsToLiteralType.ts ===
-declare function isFoo(value: string) : value is "foo";
->isFoo : (value: string) => value is "foo"
->value : string
->value : any
-
-declare function doThis(value: "foo"): void;
->doThis : (value: "foo") => void
->value : "foo"
-
-declare function doThat(value: string) : void;
->doThat : (value: string) => void
->value : string
-
-let value: string;
->value : string
-
-if (isFoo(value)) {
->isFoo(value) : boolean
->isFoo : (value: string) => value is "foo"
->value : string
-
-    doThis(value);
->doThis(value) : void
->doThis : (value: "foo") => void
->value : "foo"
-
-} else {
-    doThat(value);
->doThat(value) : void
->doThat : (value: string) => void
->value : string
-}
-
-
diff --git a/tests/baselines/reference/typeGuardNarrowsToLiteralTypeUnion.js b/tests/baselines/reference/typeGuardNarrowsToLiteralTypeUnion.js
deleted file mode 100644
index 715b362c8e0c2..0000000000000
--- a/tests/baselines/reference/typeGuardNarrowsToLiteralTypeUnion.js
+++ /dev/null
@@ -1,21 +0,0 @@
-//// [typeGuardNarrowsToLiteralTypeUnion.ts]
-declare function isFoo(value: string) : value is ("foo" | "bar");
-declare function doThis(value: "foo" | "bar"): void;
-declare function doThat(value: string) : void;
-let value: string;
-if (isFoo(value)) {
-    doThis(value);
-} else {
-    doThat(value);
-}
-
-
-
-//// [typeGuardNarrowsToLiteralTypeUnion.js]
-var value;
-if (isFoo(value)) {
-    doThis(value);
-}
-else {
-    doThat(value);
-}
diff --git a/tests/baselines/reference/typeGuardNarrowsToLiteralTypeUnion.symbols b/tests/baselines/reference/typeGuardNarrowsToLiteralTypeUnion.symbols
deleted file mode 100644
index 356fa06a06c4a..0000000000000
--- a/tests/baselines/reference/typeGuardNarrowsToLiteralTypeUnion.symbols
+++ /dev/null
@@ -1,32 +0,0 @@
-=== tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsToLiteralTypeUnion.ts ===
-declare function isFoo(value: string) : value is ("foo" | "bar");
->isFoo : Symbol(isFoo, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 0, 0))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 0, 23))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 0, 23))
-
-declare function doThis(value: "foo" | "bar"): void;
->doThis : Symbol(doThis, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 0, 65))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 1, 24))
-
-declare function doThat(value: string) : void;
->doThat : Symbol(doThat, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 1, 52))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 2, 24))
-
-let value: string;
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 3, 3))
-
-if (isFoo(value)) {
->isFoo : Symbol(isFoo, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 0, 0))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 3, 3))
-
-    doThis(value);
->doThis : Symbol(doThis, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 0, 65))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 3, 3))
-
-} else {
-    doThat(value);
->doThat : Symbol(doThat, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 1, 52))
->value : Symbol(value, Decl(typeGuardNarrowsToLiteralTypeUnion.ts, 3, 3))
-}
-
-
diff --git a/tests/baselines/reference/typeGuardNarrowsToLiteralTypeUnion.types b/tests/baselines/reference/typeGuardNarrowsToLiteralTypeUnion.types
deleted file mode 100644
index 321a8861d55f5..0000000000000
--- a/tests/baselines/reference/typeGuardNarrowsToLiteralTypeUnion.types
+++ /dev/null
@@ -1,35 +0,0 @@
-=== tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsToLiteralTypeUnion.ts ===
-declare function isFoo(value: string) : value is ("foo" | "bar");
->isFoo : (value: string) => value is "foo" | "bar"
->value : string
->value : any
-
-declare function doThis(value: "foo" | "bar"): void;
->doThis : (value: "foo" | "bar") => void
->value : "foo" | "bar"
-
-declare function doThat(value: string) : void;
->doThat : (value: string) => void
->value : string
-
-let value: string;
->value : string
-
-if (isFoo(value)) {
->isFoo(value) : boolean
->isFoo : (value: string) => value is "foo" | "bar"
->value : string
-
-    doThis(value);
->doThis(value) : void
->doThis : (value: "foo" | "bar") => void
->value : "foo" | "bar"
-
-} else {
-    doThat(value);
->doThat(value) : void
->doThat : (value: string) => void
->value : string
-}
-
-
diff --git a/tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsPrimitiveIntersection.ts b/tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsPrimitiveIntersection.ts
deleted file mode 100644
index 376a78275c83b..0000000000000
--- a/tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsPrimitiveIntersection.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-type Tag = {__tag: any};
-declare function isNonBlank(value: string) : value is (string & Tag);
-declare function doThis(value: string & Tag): void;
-declare function doThat(value: string) : void;
-let value: string;
-if (isNonBlank(value)) {
-    doThis(value);
-} else {
-    doThat(value);
-}
-
-
-const enum Tag2 {}
-declare function isNonBlank2(value: string) : value is (string & Tag2);
-declare function doThis2(value: string & Tag2): void;
-declare function doThat2(value: string) : void;
-if (isNonBlank2(value)) {
-    doThis2(value);
-} else {
-    doThat2(value);
-}
diff --git a/tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsToLiteralType.ts b/tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsToLiteralType.ts
deleted file mode 100644
index 3b7d5bba21ab7..0000000000000
--- a/tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsToLiteralType.ts
+++ /dev/null
@@ -1,10 +0,0 @@
-declare function isFoo(value: string) : value is "foo";
-declare function doThis(value: "foo"): void;
-declare function doThat(value: string) : void;
-let value: string;
-if (isFoo(value)) {
-    doThis(value);
-} else {
-    doThat(value);
-}
-
diff --git a/tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsToLiteralTypeUnion.ts b/tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsToLiteralTypeUnion.ts
deleted file mode 100644
index 8f4726160f4b2..0000000000000
--- a/tests/cases/conformance/expressions/typeGuards/typeGuardNarrowsToLiteralTypeUnion.ts
+++ /dev/null
@@ -1,10 +0,0 @@
-declare function isFoo(value: string) : value is ("foo" | "bar");
-declare function doThis(value: "foo" | "bar"): void;
-declare function doThat(value: string) : void;
-let value: string;
-if (isFoo(value)) {
-    doThis(value);
-} else {
-    doThat(value);
-}
-