diff --git a/ext/bulk_add/test.php b/ext/bulk_add/test.php
index 6ffc5fb8..2bf423b6 100644
--- a/ext/bulk_add/test.php
+++ b/ext/bulk_add/test.php
@@ -10,7 +10,7 @@ class BulkAddTest extends ShimmiePHPUnitTestCase
 
         $bae = new BulkAddEvent('asdf');
         send_event($bae);
-        $this->assertContains(
+        $this->assertStringContainsString(
             "Error, asdf is not a readable directory",
             $bae->results,
             implode("\n", $bae->results)
diff --git a/ext/comment/test.php b/ext/comment/test.php
index 357e5753..f1853a72 100644
--- a/ext/comment/test.php
+++ b/ext/comment/test.php
@@ -32,28 +32,28 @@ class CommentListTest extends ShimmiePHPUnitTestCase
         try {
             send_event(new CommentPostingEvent($image_id, $user, "Test Comment ASDFASDF"));
         } catch (CommentPostingException $e) {
-            $this->assertContains("try and be more original", $e->getMessage());
+            $this->assertStringContainsString("try and be more original", $e->getMessage());
         }
 
         # empty comment
         try {
             send_event(new CommentPostingEvent($image_id, $user, ""));
         } catch (CommentPostingException $e) {
-            $this->assertContains("Comments need text", $e->getMessage());
+            $this->assertStringContainsString("Comments need text", $e->getMessage());
         }
 
         # whitespace is still empty...
         try {
             send_event(new CommentPostingEvent($image_id, $user, " \t\r\n"));
         } catch (CommentPostingException $e) {
-            $this->assertContains("Comments need text", $e->getMessage());
+            $this->assertStringContainsString("Comments need text", $e->getMessage());
         }
 
         # repetitive (aka. gzip gives >= 10x improvement)
         try {
             send_event(new CommentPostingEvent($image_id, $user, str_repeat("U", 5000)));
         } catch (CommentPostingException $e) {
-            $this->assertContains("Comment too repetitive", $e->getMessage());
+            $this->assertStringContainsString("Comment too repetitive", $e->getMessage());
         }
 
         # test UTF8
diff --git a/ext/site_description/test.php b/ext/site_description/test.php
index 6cd01aa0..f6cdff93 100644
--- a/ext/site_description/test.php
+++ b/ext/site_description/test.php
@@ -6,7 +6,7 @@ class SiteDescriptionTest extends ShimmiePHPUnitTestCase
         global $config, $page;
         $config->set_string("site_description", "A Shimmie testbed");
         $this->get_page("post/list");
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<meta name="description" content="A Shimmie testbed">',
             $page->get_all_html_headers()
         );
@@ -17,7 +17,7 @@ class SiteDescriptionTest extends ShimmiePHPUnitTestCase
         global $config, $page;
         $config->set_string("site_keywords", "foo,bar,baz");
         $this->get_page("post/list");
-        $this->assertContains(
+        $this->assertStringContainsString(
             '<meta name="keywords" content="foo,bar,baz">',
             $page->get_all_html_headers()
         );
diff --git a/ext/upload/test.php b/ext/upload/test.php
index 8b4eb618..5e01e3ec 100644
--- a/ext/upload/test.php
+++ b/ext/upload/test.php
@@ -22,7 +22,7 @@ class UploadTest extends ShimmiePHPUnitTestCase
         try {
             $this->post_image("tests/pbx_screenshot.jpg", "pbx computer screenshot");
         } catch (UploadException $e) {
-            $this->assertContains("already has hash", $e->getMessage());
+            $this->assertStringContainsString("already has hash", $e->getMessage());
         }
     }
 
@@ -31,7 +31,7 @@ class UploadTest extends ShimmiePHPUnitTestCase
         try {
             $this->post_image("index.php", "test");
         } catch (UploadException $e) {
-            $this->assertContains("Invalid or corrupted file", $e->getMessage());
+            $this->assertStringContainsString("Invalid or corrupted file", $e->getMessage());
         }
     }
 
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 50fef9ec..ff2dd0b3 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -77,7 +77,7 @@ abstract class ShimmiePHPUnitTestCase extends \PHPUnit\Framework\TestCase
     protected function assert_title(string $title)
     {
         global $page;
-        $this->assertContains($title, $page->title);
+        $this->assertStringContainsString($title, $page->title);
     }
 
     protected function assert_no_title(string $title)
@@ -107,7 +107,7 @@ abstract class ShimmiePHPUnitTestCase extends \PHPUnit\Framework\TestCase
 
     protected function assert_text(string $text, string $section=null)
     {
-        $this->assertContains($text, $this->page_to_text($section));
+        $this->assertStringContainsString($text, $this->page_to_text($section));
     }
 
     protected function assert_no_text(string $text, string $section=null)
@@ -118,7 +118,7 @@ abstract class ShimmiePHPUnitTestCase extends \PHPUnit\Framework\TestCase
     protected function assert_content(string $content)
     {
         global $page;
-        $this->assertContains($content, $page->data);
+        $this->assertStringContainsString($content, $page->data);
     }
 
     protected function assert_no_content(string $content)