diff --git a/src/Psalm/Internal/Type/TypeExpander.php b/src/Psalm/Internal/Type/TypeExpander.php
index 40bbf2d38..ede605aae 100644
--- a/src/Psalm/Internal/Type/TypeExpander.php
+++ b/src/Psalm/Internal/Type/TypeExpander.php
@@ -519,7 +519,8 @@ class TypeExpander
             $return_type = $return_type->setTypeParams($type_params);
         } elseif ($return_type instanceof TKeyedArray) {
             $properties = $return_type->properties;
-            foreach ($properties as &$property_type) {
+            $changed = false;
+            foreach ($properties as $k => $property_type) {
                 $property_type = self::expandUnion(
                     $codebase,
                     $property_type,
@@ -533,9 +534,44 @@ class TypeExpander
                     $expand_templates,
                     $throw_on_unresolvable_constant,
                 );
+                if ($property_type !== $properties[$k]) {
+                    $changed = true;
+                    $properties[$k] = $property_type;
+                }
             }
             unset($property_type);
-            $return_type = $return_type->setProperties($properties);
+            $fallback_params = $return_type->fallback_params;
+            if ($return_type->fallback_params) {
+                foreach ($fallback_params as $k => $property_type) {
+                    $property_type = self::expandUnion(
+                        $codebase,
+                        $property_type,
+                        $self_class,
+                        $static_class_type,
+                        $parent_class,
+                        $evaluate_class_constants,
+                        $evaluate_conditional_types,
+                        $final,
+                        $expand_generic,
+                        $expand_templates,
+                        $throw_on_unresolvable_constant,
+                    );
+                    if ($property_type !== $fallback_params[$k]) {
+                        $changed = true;
+                        $fallback_params[$k] = $property_type;
+                    }
+                }
+                unset($property_type);
+            }
+            if ($changed) {
+                $return_type = new TKeyedArray(
+                    $properties,
+                    $return_type->class_strings,
+                    $fallback_params,
+                    $return_type->is_list,
+                    $return_type->from_docblock
+                );
+            }
         }
 
         if ($return_type instanceof TObjectWithProperties) {
diff --git a/src/Psalm/Type/Atomic/TKeyedArray.php b/src/Psalm/Type/Atomic/TKeyedArray.php
index 0910c7601..8339cbf4a 100644
--- a/src/Psalm/Type/Atomic/TKeyedArray.php
+++ b/src/Psalm/Type/Atomic/TKeyedArray.php
@@ -475,11 +475,32 @@ class TKeyedArray extends Atomic
             );
         }
 
-        if ($properties === $this->properties) {
+        $fallback_params = $this->fallback_params;
+
+        foreach ($fallback_params ?? [] as $offset => $property) {
+            $fallback_params[$offset] = TemplateStandinTypeReplacer::replace(
+                $property,
+                $template_result,
+                $codebase,
+                $statements_analyzer,
+                $input_type_param,
+                $input_arg_offset,
+                $calling_class,
+                $calling_function,
+                $replace,
+                $add_lower_bound,
+                null,
+                $depth
+            );
+        }
+
+
+        if ($properties === $this->properties && $fallback_params === $this->fallback_params) {
             return $this;
         }
         $cloned = clone $this;
         $cloned->properties = $properties;
+        $cloned->fallback_params = $fallback_params;
         return $cloned;
     }
 
@@ -498,7 +519,15 @@ class TKeyedArray extends Atomic
                 $codebase
             );
         }
-        if ($properties !== $this->properties) {
+        $fallback_params = $this->fallback_params;
+        foreach ($fallback_params as $offset => $property) {
+            $fallback_params[$offset] = TemplateInferredTypeReplacer::replace(
+                $property,
+                $template_result,
+                $codebase
+            );
+        }
+        if ($properties !== $this->properties || $fallback_params !== $this->fallback_params) {
             $cloned = clone $this;
             $cloned->properties = $properties;
             return $cloned;