diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/AssertionFinder.php b/src/Psalm/Internal/Analyzer/Statements/Expression/AssertionFinder.php
index 8f7bb8dcc..d17d5c3dc 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/AssertionFinder.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/AssertionFinder.php
@@ -491,6 +491,7 @@ class AssertionFinder
                         && ($var_type = $source->node_data->getType($isset_var))
                         && !$var_type->isMixed()
                         && !$var_type->possibly_undefined
+                        && !$var_type->possibly_undefined_from_try
                         && $var_name !== '$_SESSION'
                     ) {
                         $if_types[$var_name] = [['!null']];
diff --git a/tests/TryCatchTest.php b/tests/TryCatchTest.php
index affa6e22e..8a154fd5a 100644
--- a/tests/TryCatchTest.php
+++ b/tests/TryCatchTest.php
@@ -465,6 +465,16 @@ class TryCatchTest extends TestCase
                 [],
                 '8.0'
             ],
+            'issetInCatch' => [
+                '<?php
+                    function foo() : void {
+                        try {
+                            $a = 0;
+                        } catch (Exception $e) {
+                            echo isset($a) ? $a : 1;
+                        }
+                    }'
+            ],
         ];
     }