diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 10247343525..80f3d8a3eb7 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -7642,11 +7642,9 @@ namespace ts {
             if (left.flags & TypeFlags.Any || right.flags & TypeFlags.Any) {
                 return anyType;
             }
-            left = filterType(left, t => !(t.flags & TypeFlags.Nullable));
             if (left.flags & TypeFlags.Never) {
                 return right;
             }
-            right = filterType(right, t => !(t.flags & TypeFlags.Nullable));
             if (right.flags & TypeFlags.Never) {
                 return left;
             }
diff --git a/tests/baselines/reference/spreadUnion.symbols b/tests/baselines/reference/spreadUnion.symbols
index 40a63d56d49..bef8f5522d7 100644
--- a/tests/baselines/reference/spreadUnion.symbols
+++ b/tests/baselines/reference/spreadUnion.symbols
@@ -1,4 +1,4 @@
-=== tests/cases/compiler/spreadUnion.ts ===
+=== tests/cases/conformance/types/spread/spreadUnion.ts ===
 var union: { a: number } | { b: string };
 >union : Symbol(union, Decl(spreadUnion.ts, 0, 3))
 >a : Symbol(a, Decl(spreadUnion.ts, 0, 12))
diff --git a/tests/baselines/reference/spreadUnion.types b/tests/baselines/reference/spreadUnion.types
index 9e5ac1cffd5..fb1ef5f2018 100644
--- a/tests/baselines/reference/spreadUnion.types
+++ b/tests/baselines/reference/spreadUnion.types
@@ -1,4 +1,4 @@
-=== tests/cases/compiler/spreadUnion.ts ===
+=== tests/cases/conformance/types/spread/spreadUnion.ts ===
 var union: { a: number } | { b: string };
 >union : { a: number; } | { b: string; }
 >a : number
diff --git a/tests/baselines/reference/spreadUnion2.js b/tests/baselines/reference/spreadUnion2.js
index b98046463c3..6e49770617a 100644
--- a/tests/baselines/reference/spreadUnion2.js
+++ b/tests/baselines/reference/spreadUnion2.js
@@ -3,25 +3,25 @@ declare const undefinedUnion: { a: number } | undefined;
 declare const nullUnion: { b: number } | null;
 declare const nullAndUndefinedUnion: null | undefined;
 
-var o1: { a: number };
+var o1: {} | { a: number };
 var o1 = { ...undefinedUnion };
 
-var o2: { b: number };
+var o2: {} | { b: number };
 var o2 = { ...nullUnion };
 
-var o3: { a: number, b: number };
+var o3: {} | { b: number } | { a: number } | { a: number, b: number };
 var o3 = { ...undefinedUnion, ...nullUnion };
 var o3 = { ...nullUnion, ...undefinedUnion };
 
-var o4: { a: number };
+var o4: {} | { a: number };
 var o4 = { ...undefinedUnion, ...undefinedUnion };
 
-var o5: { b: number };
+var o5: {} | { b: number };
 var o5 = { ...nullUnion, ...nullUnion };
 
-var o6: { };
 var o6 = { ...nullAndUndefinedUnion, ...nullAndUndefinedUnion };
-var o6 = { ...nullAndUndefinedUnion };
+var o7 = { ...nullAndUndefinedUnion };
+
 
 //// [spreadUnion2.js]
 var __assign = (this && this.__assign) || Object.assign || function(t) {
@@ -43,6 +43,5 @@ var o4;
 var o4 = __assign({}, undefinedUnion, undefinedUnion);
 var o5;
 var o5 = __assign({}, nullUnion, nullUnion);
-var o6;
 var o6 = __assign({}, nullAndUndefinedUnion, nullAndUndefinedUnion);
-var o6 = __assign({}, nullAndUndefinedUnion);
+var o7 = __assign({}, nullAndUndefinedUnion);
diff --git a/tests/baselines/reference/spreadUnion2.symbols b/tests/baselines/reference/spreadUnion2.symbols
index 05703fc32bd..c4d1f19b6d9 100644
--- a/tests/baselines/reference/spreadUnion2.symbols
+++ b/tests/baselines/reference/spreadUnion2.symbols
@@ -1,4 +1,4 @@
-=== tests/cases/compiler/spreadUnion2.ts ===
+=== tests/cases/conformance/types/spread/spreadUnion2.ts ===
 declare const undefinedUnion: { a: number } | undefined;
 >undefinedUnion : Symbol(undefinedUnion, Decl(spreadUnion2.ts, 0, 13))
 >a : Symbol(a, Decl(spreadUnion2.ts, 0, 31))
@@ -10,26 +10,28 @@ declare const nullUnion: { b: number } | null;
 declare const nullAndUndefinedUnion: null | undefined;
 >nullAndUndefinedUnion : Symbol(nullAndUndefinedUnion, Decl(spreadUnion2.ts, 2, 13))
 
-var o1: { a: number };
+var o1: {} | { a: number };
 >o1 : Symbol(o1, Decl(spreadUnion2.ts, 4, 3), Decl(spreadUnion2.ts, 5, 3))
->a : Symbol(a, Decl(spreadUnion2.ts, 4, 9))
+>a : Symbol(a, Decl(spreadUnion2.ts, 4, 14))
 
 var o1 = { ...undefinedUnion };
 >o1 : Symbol(o1, Decl(spreadUnion2.ts, 4, 3), Decl(spreadUnion2.ts, 5, 3))
 >undefinedUnion : Symbol(undefinedUnion, Decl(spreadUnion2.ts, 0, 13))
 
-var o2: { b: number };
+var o2: {} | { b: number };
 >o2 : Symbol(o2, Decl(spreadUnion2.ts, 7, 3), Decl(spreadUnion2.ts, 8, 3))
->b : Symbol(b, Decl(spreadUnion2.ts, 7, 9))
+>b : Symbol(b, Decl(spreadUnion2.ts, 7, 14))
 
 var o2 = { ...nullUnion };
 >o2 : Symbol(o2, Decl(spreadUnion2.ts, 7, 3), Decl(spreadUnion2.ts, 8, 3))
 >nullUnion : Symbol(nullUnion, Decl(spreadUnion2.ts, 1, 13))
 
-var o3: { a: number, b: number };
+var o3: {} | { b: number } | { a: number } | { a: number, b: number };
 >o3 : Symbol(o3, Decl(spreadUnion2.ts, 10, 3), Decl(spreadUnion2.ts, 11, 3), Decl(spreadUnion2.ts, 12, 3))
->a : Symbol(a, Decl(spreadUnion2.ts, 10, 9))
->b : Symbol(b, Decl(spreadUnion2.ts, 10, 20))
+>b : Symbol(b, Decl(spreadUnion2.ts, 10, 14))
+>a : Symbol(a, Decl(spreadUnion2.ts, 10, 30))
+>a : Symbol(a, Decl(spreadUnion2.ts, 10, 46))
+>b : Symbol(b, Decl(spreadUnion2.ts, 10, 57))
 
 var o3 = { ...undefinedUnion, ...nullUnion };
 >o3 : Symbol(o3, Decl(spreadUnion2.ts, 10, 3), Decl(spreadUnion2.ts, 11, 3), Decl(spreadUnion2.ts, 12, 3))
@@ -41,33 +43,30 @@ var o3 = { ...nullUnion, ...undefinedUnion };
 >nullUnion : Symbol(nullUnion, Decl(spreadUnion2.ts, 1, 13))
 >undefinedUnion : Symbol(undefinedUnion, Decl(spreadUnion2.ts, 0, 13))
 
-var o4: { a: number };
+var o4: {} | { a: number };
 >o4 : Symbol(o4, Decl(spreadUnion2.ts, 14, 3), Decl(spreadUnion2.ts, 15, 3))
->a : Symbol(a, Decl(spreadUnion2.ts, 14, 9))
+>a : Symbol(a, Decl(spreadUnion2.ts, 14, 14))
 
 var o4 = { ...undefinedUnion, ...undefinedUnion };
 >o4 : Symbol(o4, Decl(spreadUnion2.ts, 14, 3), Decl(spreadUnion2.ts, 15, 3))
 >undefinedUnion : Symbol(undefinedUnion, Decl(spreadUnion2.ts, 0, 13))
 >undefinedUnion : Symbol(undefinedUnion, Decl(spreadUnion2.ts, 0, 13))
 
-var o5: { b: number };
+var o5: {} | { b: number };
 >o5 : Symbol(o5, Decl(spreadUnion2.ts, 17, 3), Decl(spreadUnion2.ts, 18, 3))
->b : Symbol(b, Decl(spreadUnion2.ts, 17, 9))
+>b : Symbol(b, Decl(spreadUnion2.ts, 17, 14))
 
 var o5 = { ...nullUnion, ...nullUnion };
 >o5 : Symbol(o5, Decl(spreadUnion2.ts, 17, 3), Decl(spreadUnion2.ts, 18, 3))
 >nullUnion : Symbol(nullUnion, Decl(spreadUnion2.ts, 1, 13))
 >nullUnion : Symbol(nullUnion, Decl(spreadUnion2.ts, 1, 13))
 
-var o6: { };
->o6 : Symbol(o6, Decl(spreadUnion2.ts, 20, 3), Decl(spreadUnion2.ts, 21, 3), Decl(spreadUnion2.ts, 22, 3))
-
 var o6 = { ...nullAndUndefinedUnion, ...nullAndUndefinedUnion };
->o6 : Symbol(o6, Decl(spreadUnion2.ts, 20, 3), Decl(spreadUnion2.ts, 21, 3), Decl(spreadUnion2.ts, 22, 3))
+>o6 : Symbol(o6, Decl(spreadUnion2.ts, 20, 3))
 >nullAndUndefinedUnion : Symbol(nullAndUndefinedUnion, Decl(spreadUnion2.ts, 2, 13))
 >nullAndUndefinedUnion : Symbol(nullAndUndefinedUnion, Decl(spreadUnion2.ts, 2, 13))
 
-var o6 = { ...nullAndUndefinedUnion };
->o6 : Symbol(o6, Decl(spreadUnion2.ts, 20, 3), Decl(spreadUnion2.ts, 21, 3), Decl(spreadUnion2.ts, 22, 3))
+var o7 = { ...nullAndUndefinedUnion };
+>o7 : Symbol(o7, Decl(spreadUnion2.ts, 21, 3))
 >nullAndUndefinedUnion : Symbol(nullAndUndefinedUnion, Decl(spreadUnion2.ts, 2, 13))
 
diff --git a/tests/baselines/reference/spreadUnion2.types b/tests/baselines/reference/spreadUnion2.types
index 97fbb9838c7..ea3364f296b 100644
--- a/tests/baselines/reference/spreadUnion2.types
+++ b/tests/baselines/reference/spreadUnion2.types
@@ -1,4 +1,4 @@
-=== tests/cases/compiler/spreadUnion2.ts ===
+=== tests/cases/conformance/types/spread/spreadUnion2.ts ===
 declare const undefinedUnion: { a: number } | undefined;
 >undefinedUnion : { a: number; } | undefined
 >a : number
@@ -12,72 +12,71 @@ declare const nullAndUndefinedUnion: null | undefined;
 >nullAndUndefinedUnion : null | undefined
 >null : null
 
-var o1: { a: number };
->o1 : { a: number; }
+var o1: {} | { a: number };
+>o1 : {} | { a: number; }
 >a : number
 
 var o1 = { ...undefinedUnion };
->o1 : { a: number; }
->{ ...undefinedUnion } : { a: number; }
+>o1 : {} | { a: number; }
+>{ ...undefinedUnion } : {} | { a: number; }
 >undefinedUnion : { a: number; } | undefined
 
-var o2: { b: number };
->o2 : { b: number; }
+var o2: {} | { b: number };
+>o2 : {} | { b: number; }
 >b : number
 
 var o2 = { ...nullUnion };
->o2 : { b: number; }
->{ ...nullUnion } : { b: number; }
+>o2 : {} | { b: number; }
+>{ ...nullUnion } : {} | { b: number; }
 >nullUnion : { b: number; } | null
 
-var o3: { a: number, b: number };
->o3 : { a: number; b: number; }
+var o3: {} | { b: number } | { a: number } | { a: number, b: number };
+>o3 : {} | { b: number; } | { a: number; } | { a: number; b: number; }
+>b : number
+>a : number
 >a : number
 >b : number
 
 var o3 = { ...undefinedUnion, ...nullUnion };
->o3 : { a: number; b: number; }
->{ ...undefinedUnion, ...nullUnion } : { b: number; a: number; }
+>o3 : {} | { b: number; } | { a: number; } | { a: number; b: number; }
+>{ ...undefinedUnion, ...nullUnion } : {} | { b: number; } | { a: number; } | { b: number; a: number; }
 >undefinedUnion : { a: number; } | undefined
 >nullUnion : { b: number; } | null
 
 var o3 = { ...nullUnion, ...undefinedUnion };
->o3 : { a: number; b: number; }
->{ ...nullUnion, ...undefinedUnion } : { a: number; b: number; }
+>o3 : {} | { b: number; } | { a: number; } | { a: number; b: number; }
+>{ ...nullUnion, ...undefinedUnion } : {} | { a: number; } | { b: number; } | { a: number; b: number; }
 >nullUnion : { b: number; } | null
 >undefinedUnion : { a: number; } | undefined
 
-var o4: { a: number };
->o4 : { a: number; }
+var o4: {} | { a: number };
+>o4 : {} | { a: number; }
 >a : number
 
 var o4 = { ...undefinedUnion, ...undefinedUnion };
->o4 : { a: number; }
->{ ...undefinedUnion, ...undefinedUnion } : { a: number; }
+>o4 : {} | { a: number; }
+>{ ...undefinedUnion, ...undefinedUnion } : {} | { a: number; } | { a: number; } | { a: number; }
 >undefinedUnion : { a: number; } | undefined
 >undefinedUnion : { a: number; } | undefined
 
-var o5: { b: number };
->o5 : { b: number; }
+var o5: {} | { b: number };
+>o5 : {} | { b: number; }
 >b : number
 
 var o5 = { ...nullUnion, ...nullUnion };
->o5 : { b: number; }
->{ ...nullUnion, ...nullUnion } : { b: number; }
+>o5 : {} | { b: number; }
+>{ ...nullUnion, ...nullUnion } : {} | { b: number; } | { b: number; } | { b: number; }
 >nullUnion : { b: number; } | null
 >nullUnion : { b: number; } | null
 
-var o6: { };
->o6 : {}
-
 var o6 = { ...nullAndUndefinedUnion, ...nullAndUndefinedUnion };
->o6 : {}
->{ ...nullAndUndefinedUnion, ...nullAndUndefinedUnion } : {}
+>o6 : {} | {} | {} | {}
+>{ ...nullAndUndefinedUnion, ...nullAndUndefinedUnion } : {} | {} | {} | {}
 >nullAndUndefinedUnion : null | undefined
 >nullAndUndefinedUnion : null | undefined
 
-var o6 = { ...nullAndUndefinedUnion };
->o6 : {}
->{ ...nullAndUndefinedUnion } : {}
+var o7 = { ...nullAndUndefinedUnion };
+>o7 : {} | {}
+>{ ...nullAndUndefinedUnion } : {} | {}
 >nullAndUndefinedUnion : null | undefined
 
diff --git a/tests/baselines/reference/spreadUnion3.errors.txt b/tests/baselines/reference/spreadUnion3.errors.txt
new file mode 100644
index 00000000000..5f5b620685c
--- /dev/null
+++ b/tests/baselines/reference/spreadUnion3.errors.txt
@@ -0,0 +1,31 @@
+tests/cases/conformance/types/spread/spreadUnion3.ts(2,5): error TS2322: Type '{ y: number; } | { y: string; }' is not assignable to type '{ y: string; }'.
+  Type '{ y: number; }' is not assignable to type '{ y: string; }'.
+    Types of property 'y' are incompatible.
+      Type 'number' is not assignable to type 'string'.
+tests/cases/conformance/types/spread/spreadUnion3.ts(9,23): error TS2339: Property 'a' does not exist on type '{} | {} | { a: number; }'.
+  Property 'a' does not exist on type '{}'.
+
+
+==== tests/cases/conformance/types/spread/spreadUnion3.ts (2 errors) ====
+    function f(x: { y: string } | undefined): { y: string } {
+        return { y: 123, ...x } // y: string | number
+        ~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2322: Type '{ y: number; } | { y: string; }' is not assignable to type '{ y: string; }'.
+!!! error TS2322:   Type '{ y: number; }' is not assignable to type '{ y: string; }'.
+!!! error TS2322:     Types of property 'y' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'string'.
+    }
+    f(undefined)
+    
+    
+    function g(t?: { a: number } | null): void {
+        let b = { ...t };
+        let c: number = b.a;  // might not have 'a'
+                          ~
+!!! error TS2339: Property 'a' does not exist on type '{} | {} | { a: number; }'.
+!!! error TS2339:   Property 'a' does not exist on type '{}'.
+    }
+    g()
+    g(undefined)
+    g(null)
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/spreadUnion3.js b/tests/baselines/reference/spreadUnion3.js
new file mode 100644
index 00000000000..2aaf9efeb78
--- /dev/null
+++ b/tests/baselines/reference/spreadUnion3.js
@@ -0,0 +1,36 @@
+//// [spreadUnion3.ts]
+function f(x: { y: string } | undefined): { y: string } {
+    return { y: 123, ...x } // y: string | number
+}
+f(undefined)
+
+
+function g(t?: { a: number } | null): void {
+    let b = { ...t };
+    let c: number = b.a;  // might not have 'a'
+}
+g()
+g(undefined)
+g(null)
+
+
+//// [spreadUnion3.js]
+var __assign = (this && this.__assign) || Object.assign || function(t) {
+    for (var s, i = 1, n = arguments.length; i < n; i++) {
+        s = arguments[i];
+        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+            t[p] = s[p];
+    }
+    return t;
+};
+function f(x) {
+    return __assign({ y: 123 }, x); // y: string | number
+}
+f(undefined);
+function g(t) {
+    var b = __assign({}, t);
+    var c = b.a; // might not have 'a'
+}
+g();
+g(undefined);
+g(null);
diff --git a/tests/cases/compiler/spreadUnion.ts b/tests/cases/conformance/types/spread/spreadUnion.ts
similarity index 100%
rename from tests/cases/compiler/spreadUnion.ts
rename to tests/cases/conformance/types/spread/spreadUnion.ts
diff --git a/tests/cases/compiler/spreadUnion2.ts b/tests/cases/conformance/types/spread/spreadUnion2.ts
similarity index 67%
rename from tests/cases/compiler/spreadUnion2.ts
rename to tests/cases/conformance/types/spread/spreadUnion2.ts
index 25dba81c0df..e2f72879915 100644
--- a/tests/cases/compiler/spreadUnion2.ts
+++ b/tests/cases/conformance/types/spread/spreadUnion2.ts
@@ -4,22 +4,21 @@ declare const undefinedUnion: { a: number } | undefined;
 declare const nullUnion: { b: number } | null;
 declare const nullAndUndefinedUnion: null | undefined;
 
-var o1: { a: number };
+var o1: {} | { a: number };
 var o1 = { ...undefinedUnion };
 
-var o2: { b: number };
+var o2: {} | { b: number };
 var o2 = { ...nullUnion };
 
-var o3: { a: number, b: number };
+var o3: {} | { b: number } | { a: number } | { a: number, b: number };
 var o3 = { ...undefinedUnion, ...nullUnion };
 var o3 = { ...nullUnion, ...undefinedUnion };
 
-var o4: { a: number };
+var o4: {} | { a: number };
 var o4 = { ...undefinedUnion, ...undefinedUnion };
 
-var o5: { b: number };
+var o5: {} | { b: number };
 var o5 = { ...nullUnion, ...nullUnion };
 
-var o6: { };
 var o6 = { ...nullAndUndefinedUnion, ...nullAndUndefinedUnion };
-var o6 = { ...nullAndUndefinedUnion };
\ No newline at end of file
+var o7 = { ...nullAndUndefinedUnion };
diff --git a/tests/cases/conformance/types/spread/spreadUnion3.ts b/tests/cases/conformance/types/spread/spreadUnion3.ts
new file mode 100644
index 00000000000..c16acbdf7d3
--- /dev/null
+++ b/tests/cases/conformance/types/spread/spreadUnion3.ts
@@ -0,0 +1,14 @@
+// @strictNullChecks: true
+function f(x: { y: string } | undefined): { y: string } {
+    return { y: 123, ...x } // y: string | number
+}
+f(undefined)
+
+
+function g(t?: { a: number } | null): void {
+    let b = { ...t };
+    let c: number = b.a;  // might not have 'a'
+}
+g()
+g(undefined)
+g(null)