diff --git a/src/Psalm/Internal/Type/Comparator/ObjectComparator.php b/src/Psalm/Internal/Type/Comparator/ObjectComparator.php
index a0ae71166..5b2ea66ea 100644
--- a/src/Psalm/Internal/Type/Comparator/ObjectComparator.php
+++ b/src/Psalm/Internal/Type/Comparator/ObjectComparator.php
@@ -124,7 +124,7 @@ class ObjectComparator
                 );
             }
 
-            foreach ($intersection_input_types as $intersection_input_type) {
+            foreach ($intersection_input_types as $intersection_input_key => $intersection_input_type) {
                 $input_was_static = false;
 
                 if ($intersection_input_type instanceof TIterable) {
@@ -239,7 +239,10 @@ class ObjectComparator
                     $input_type_is_interface = $codebase->interfaceExists($intersection_input_type_lower);
                     $container_type_is_interface = $codebase->interfaceExists($intersection_container_type_lower);
 
-                    if ($allow_interface_equality && $container_type_is_interface) {
+                    if ($allow_interface_equality
+                        && $container_type_is_interface
+                        && ($input_type_is_interface || !isset($intersection_container_types[$intersection_input_key]))
+                    ) {
                         continue 2;
                     }
 
diff --git a/tests/InterfaceTest.php b/tests/InterfaceTest.php
index b5b946faa..1c96e7c1e 100644
--- a/tests/InterfaceTest.php
+++ b/tests/InterfaceTest.php
@@ -686,6 +686,21 @@ class InterfaceTest extends TestCase
                         $f->m()->m();
                     }'
             ],
+            'dontModifyAfterUnnecessaryAssertion' => [
+                '<?php
+                    class A {}
+                    interface I {}
+
+                    /**
+                     * @param A&I $a
+                     * @return A&I
+                     */
+                    function foo(I $a) {
+                        /** @psalm-suppress RedundantConditionGivenDocblockType */
+                        assert($a instanceof A);
+                        return $a;
+                    }'
+            ],
         ];
     }