diff --git a/tests/func_015.phpt b/tests/func_015.phpt
index 067634d..944cf09 100644
--- a/tests/func_015.phpt
+++ b/tests/func_015.phpt
@@ -35,6 +35,11 @@ foreach (['', (object) [], '1234', 4.5, true, new \DateTimeImmutable(), new \Dat
     } catch (TypeError $e) {
         $message = $e->getMessage();
 
+        if (PHP_VERSION_ID >= 80300) {
+            // PHP 8.3+ outputs "true given" instead of "bool given".
+            $message = str_replace('true given', 'bool given', $message);
+        }
+
         // Workaround exception message not including type in PHP 7 so the same test can be used for both.
         if (PHP_MAJOR_VERSION === 7) {
             $message = str_replace('N/A given', var_type($input).' given', $message);
diff --git a/tests/func_016.phpt b/tests/func_016.phpt
index 6a024b7..75e5b5e 100644
--- a/tests/func_016.phpt
+++ b/tests/func_016.phpt
@@ -35,6 +35,11 @@ foreach (['', (object) [], '1234', 4.5, true, new \DateTimeImmutable(), new \Dat
     } catch (TypeError $e) {
         $message = $e->getMessage();
 
+        if (PHP_VERSION_ID >= 80300) {
+            // PHP 8.3+ outputs "true given" instead of "bool given".
+            $message = str_replace('true given', 'bool given', $message);
+        }
+
         // Workaround exception message not including type in PHP 7 so the same test can be used for both.
         if (PHP_MAJOR_VERSION === 7) {
             $message = str_replace('N/A given', var_type($input).' given', $message);
diff --git a/tests/func_017.phpt b/tests/func_017.phpt
index c53e21e..074598b 100644
--- a/tests/func_017.phpt
+++ b/tests/func_017.phpt
@@ -24,5 +24,5 @@ timecop_scale\(\)( expects parameter 1 to be|: Argument #1 \(\$scale\) must be o
 timecop_scale\(\)( expects parameter 1 to be|: Argument #1 \(\$scale\) must be of type) (integer|int), (object|stdClass) given
 timecop_scale\(\)( expects parameter 1 to be|: Argument #1 \(\$scale\) must be of type) (integer|int), string given
 timecop_scale\(\)( expects parameter 1 to be|: Argument #1 \(\$scale\) must be of type) (integer|int), float given
-timecop_scale\(\)( expects parameter 1 to be|: Argument #1 \(\$scale\) must be of type) (integer|int), (bool|boolean) given
+timecop_scale\(\)( expects parameter 1 to be|: Argument #1 \(\$scale\) must be of type) (integer|int), (bool|boolean|true) given
 bool\(false\)