diff --git a/phpunit/code/re-assign-array-to-bool.php b/phpunit/code/re-assign-array-to-bool.php
new file mode 100644
index 00000000..e15cfe71
--- /dev/null
+++ b/phpunit/code/re-assign-array-to-bool.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = true;
+    $x = [1, 2];
+}
diff --git a/phpunit/code/re-assign-array-to-float.php b/phpunit/code/re-assign-array-to-float.php
new file mode 100644
index 00000000..13e3c426
--- /dev/null
+++ b/phpunit/code/re-assign-array-to-float.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = 3.14;
+    $x = [1, 2];
+}
diff --git a/phpunit/code/re-assign-array-to-int.php b/phpunit/code/re-assign-array-to-int.php
new file mode 100644
index 00000000..48689227
--- /dev/null
+++ b/phpunit/code/re-assign-array-to-int.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = 42;
+    $x = [1, 2];
+}
diff --git a/phpunit/code/re-assign-array-to-obj.php b/phpunit/code/re-assign-array-to-obj.php
new file mode 100644
index 00000000..f4060f37
--- /dev/null
+++ b/phpunit/code/re-assign-array-to-obj.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $obj = new stdClass();
+    $obj = [1, 2];
+}
diff --git a/phpunit/code/re-assign-bool-to-array.php b/phpunit/code/re-assign-bool-to-array.php
new file mode 100644
index 00000000..ed42fc0c
--- /dev/null
+++ b/phpunit/code/re-assign-bool-to-array.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = [1, 2];
+    $x = true;
+}
diff --git a/phpunit/code/re-assign-bool-to-obj.php b/phpunit/code/re-assign-bool-to-obj.php
new file mode 100644
index 00000000..e53b64d7
--- /dev/null
+++ b/phpunit/code/re-assign-bool-to-obj.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $obj = new stdClass();
+    $obj = true;
+}
diff --git a/phpunit/code/re-assign-float-to-array.php b/phpunit/code/re-assign-float-to-array.php
new file mode 100644
index 00000000..a9e347f1
--- /dev/null
+++ b/phpunit/code/re-assign-float-to-array.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = [1, 2];
+    $x = 3.14;
+}
diff --git a/phpunit/code/re-assign-float-to-obj.php b/phpunit/code/re-assign-float-to-obj.php
new file mode 100644
index 00000000..8f5a88a9
--- /dev/null
+++ b/phpunit/code/re-assign-float-to-obj.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $obj = new stdClass();
+    $obj = 3.14;
+}
diff --git a/phpunit/code/re-assign-int-to-array.php b/phpunit/code/re-assign-int-to-array.php
new file mode 100644
index 00000000..7ed623d0
--- /dev/null
+++ b/phpunit/code/re-assign-int-to-array.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = [1, 2];
+    $x = 42;
+}
diff --git a/phpunit/code/re-assign-int-to-obj.php b/phpunit/code/re-assign-int-to-obj.php
new file mode 100644
index 00000000..7ec60879
--- /dev/null
+++ b/phpunit/code/re-assign-int-to-obj.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $obj = new stdClass();
+    $obj = 42;
+}
diff --git a/phpunit/code/re-assign-obj-to-array.php b/phpunit/code/re-assign-obj-to-array.php
index 15437dde..d5b8065a 100644
--- a/phpunit/code/re-assign-obj-to-array.php
+++ b/phpunit/code/re-assign-obj-to-array.php
@@ -1,7 +1,8 @@
 <?php
+use native_types;
 
 function main()
 {
     $obj = [];
     $obj = new stdClass();
-}
\ No newline at end of file
+}
diff --git a/phpunit/code/re-assign-obj-to-bool.php b/phpunit/code/re-assign-obj-to-bool.php
new file mode 100644
index 00000000..74142d8e
--- /dev/null
+++ b/phpunit/code/re-assign-obj-to-bool.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = true;
+    $x = new stdClass();
+}
diff --git a/phpunit/code/re-assign-obj-to-float.php b/phpunit/code/re-assign-obj-to-float.php
new file mode 100644
index 00000000..39c53ada
--- /dev/null
+++ b/phpunit/code/re-assign-obj-to-float.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = 3.14;
+    $x = new stdClass();
+}
diff --git a/phpunit/code/re-assign-obj-to-int.php b/phpunit/code/re-assign-obj-to-int.php
new file mode 100644
index 00000000..9f0c6db4
--- /dev/null
+++ b/phpunit/code/re-assign-obj-to-int.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = 42;
+    $x = new stdClass();
+}
diff --git a/phpunit/code/re-assign-obj-to-str.php b/phpunit/code/re-assign-obj-to-str.php
new file mode 100644
index 00000000..538f65c1
--- /dev/null
+++ b/phpunit/code/re-assign-obj-to-str.php
@@ -0,0 +1,8 @@
+<?php
+declare(strict_types=1);
+use native_types;
+function main()
+{
+    $x = "hello";
+    $x = new stdClass();
+}
diff --git a/phpunit/code/re-assign-str-to-array.php b/phpunit/code/re-assign-str-to-array.php
new file mode 100644
index 00000000..b9e43730
--- /dev/null
+++ b/phpunit/code/re-assign-str-to-array.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = [1, 2];
+    $x = "hello";
+}
diff --git a/phpunit/code/re-assign-str-to-bool.php b/phpunit/code/re-assign-str-to-bool.php
new file mode 100644
index 00000000..9f60be78
--- /dev/null
+++ b/phpunit/code/re-assign-str-to-bool.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = true;
+    $x = "hello";
+}
diff --git a/phpunit/code/re-assign-str-to-float.php b/phpunit/code/re-assign-str-to-float.php
new file mode 100644
index 00000000..a9dbfe1c
--- /dev/null
+++ b/phpunit/code/re-assign-str-to-float.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = 3.14;
+    $x = "hello";
+}
diff --git a/phpunit/code/re-assign-str-to-int.php b/phpunit/code/re-assign-str-to-int.php
new file mode 100644
index 00000000..272ab966
--- /dev/null
+++ b/phpunit/code/re-assign-str-to-int.php
@@ -0,0 +1,7 @@
+<?php
+use native_types;
+function main()
+{
+    $x = 42;
+    $x = "hello";
+}
diff --git a/phpunit/code/re-assign-str-to-obj.php b/phpunit/code/re-assign-str-to-obj.php
deleted file mode 100644
index 53dbca11..00000000
--- a/phpunit/code/re-assign-str-to-obj.php
+++ /dev/null
@@ -1,15 +0,0 @@
-<?php
-function bar()
-{
-    return 'string';
-}
-function foo(stdClass $o)
-{
-    $o = bar();
-}
-
-function main()
-{
-    $obj = new stdClass();
-    foo($obj);
-}
\ No newline at end of file
diff --git a/phpunit/src/AssignTest.php b/phpunit/src/AssignTest.php
index 3c8eb131..e425dae8 100644
--- a/phpunit/src/AssignTest.php
+++ b/phpunit/src/AssignTest.php
@@ -2,9 +2,11 @@
 
 class AssignTest extends \BaseTest
 {
+    // === Existing tests ===
+
     public function testReAssign()
     {
-        $this->exec('Cannot re-assign variable', 're-assign.php');
+        $this->exec('Cannot re-assign `$obj` from `php::Str` to `php::Object`', 're-assign.php');
     }
 
     public function testAssignClass()
@@ -51,4 +53,107 @@ class AssignTest extends \BaseTest
             'std-unsafe-ptr-argument-requires-container.php'
         );
     }
+
+    // === Object value assigned to non-object variable (right side is New_ expr) ===
+
+    public function testObjectToInt()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Object` to `php::Int`", 're-assign-obj-to-int.php');
+    }
+
+    public function testObjectToFloat()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Object` to `php::Float`", 're-assign-obj-to-float.php');
+    }
+
+    public function testObjectToBool()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Object` to `php::Bool`", 're-assign-obj-to-bool.php');
+    }
+
+    public function testObjectToStr()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Object` to `php::Str`", 're-assign-obj-to-str.php');
+    }
+
+    public function testObjectToArray()
+    {
+        $this->exec("Cannot re-assign `\$obj` from `php::Object` to `php::Array`", 're-assign-obj-to-array.php');
+    }
+
+    // === Non-object value assigned to Object variable ===
+
+    public function testIntToObject()
+    {
+        $this->exec("Cannot re-assign `\$obj` from `php::Int` to `php::Object`", 're-assign-int-to-obj.php');
+    }
+
+    public function testFloatToObject()
+    {
+        $this->exec("Cannot re-assign `\$obj` from `php::Float` to `php::Object`", 're-assign-float-to-obj.php');
+    }
+
+    public function testBoolToObject()
+    {
+        $this->exec("Cannot re-assign `\$obj` from `php::Bool` to `php::Object`", 're-assign-bool-to-obj.php');
+    }
+
+    public function testArrayToObject()
+    {
+        $this->exec("Cannot re-assign `\$obj` from `php::Array` to `php::Object`", 're-assign-array-to-obj.php');
+    }
+
+    // === Str / Array value assigned to non-object scalar variable ===
+
+    public function testStrToInt()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Str` to `php::Int`", 're-assign-str-to-int.php');
+    }
+
+    public function testArrayToInt()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Array` to `php::Int`", 're-assign-array-to-int.php');
+    }
+
+    public function testStrToFloat()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Str` to `php::Float`", 're-assign-str-to-float.php');
+    }
+
+    public function testArrayToFloat()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Array` to `php::Float`", 're-assign-array-to-float.php');
+    }
+
+    public function testStrToBool()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Str` to `php::Bool`", 're-assign-str-to-bool.php');
+    }
+
+    public function testArrayToBool()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Array` to `php::Bool`", 're-assign-array-to-bool.php');
+    }
+
+    // === Scalar value assigned to Array variable ===
+
+    public function testIntToArray()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Int` to `php::Array`", 're-assign-int-to-array.php');
+    }
+
+    public function testFloatToArray()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Float` to `php::Array`", 're-assign-float-to-array.php');
+    }
+
+    public function testBoolToArray()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Bool` to `php::Array`", 're-assign-bool-to-array.php');
+    }
+
+    public function testStrToArray()
+    {
+        $this->exec("Cannot re-assign `\$x` from `php::Str` to `php::Array`", 're-assign-str-to-array.php');
+    }
 }