diff --git a/classes/db/migrations.php b/classes/db/migrations.php
index ffce2af5f..d63736987 100644
--- a/classes/db/migrations.php
+++ b/classes/db/migrations.php
@@ -17,7 +17,7 @@ class Db_Migrations {
 
 	function initialize_for_plugin(Plugin $plugin, bool $base_is_latest = true, string $schema_suffix = "sql"): void {
 		$plugin_dir = PluginHost::getInstance()->get_plugin_dir($plugin);
-		$this->initialize($plugin_dir . "/${schema_suffix}",
+		$this->initialize("{$plugin_dir}/{$schema_suffix}",
 			strtolower("ttrss_migrations_plugin_" . get_class($plugin)),
 			$base_is_latest);
 	}
@@ -31,7 +31,7 @@ class Db_Migrations {
 	}
 
 	private function set_version(int $version): void {
-		Debug::log("Updating table {$this->migrations_table} with version ${version}...", Debug::LOG_EXTENDED);
+		Debug::log("Updating table {$this->migrations_table} with version {$version}...", Debug::LOG_EXTENDED);
 
 		$sth = $this->pdo->query("SELECT * FROM {$this->migrations_table}");
 
@@ -170,7 +170,7 @@ class Db_Migrations {
 			try {
 				$this->migrate_to($i);
 			} catch (PDOException $e) {
-				user_error("Failed to apply migration ${i} for {$this->migrations_table}: " . $e->getMessage(), E_USER_WARNING);
+				user_error("Failed to apply migration {$i} for {$this->migrations_table}: " . $e->getMessage(), E_USER_WARNING);
 				return false;
 				//throw $e;
 			}
@@ -184,7 +184,7 @@ class Db_Migrations {
 	 */
 	private function get_lines(int $version) : array {
 		if ($version > 0)
-			$filename = "{$this->migrations_path}/${version}.sql";
+			$filename = "{$this->migrations_path}/{$version}.sql";
 		else
 			$filename = "{$this->base_path}/{$this->base_filename}";
 
@@ -196,7 +196,7 @@ class Db_Migrations {
 				fn($line) => strlen(trim($line)) > 0 && !in_array(strtolower($line), ["begin", "commit"]));
 
 		} else {
-			user_error("Requested schema file ${filename} not found.", E_USER_ERROR);
+			user_error("Requested schema file {$filename} not found.", E_USER_ERROR);
 			return [];
 		}
 	}
diff --git a/classes/diskcache.php b/classes/diskcache.php
index 01c713b99..1df8daf15 100644
--- a/classes/diskcache.php
+++ b/classes/diskcache.php
@@ -306,7 +306,7 @@ class DiskCache {
 		if ($fake_extension)
 			$fake_extension = ".$fake_extension";
 
-		header("Content-Disposition: inline; filename=\"${filename}${fake_extension}\"");
+		header("Content-Disposition: inline; filename=\"{$filename}{$fake_extension}\"");
 
 		return $this->send_local_file($this->get_full_path($filename));
 	}
diff --git a/classes/feeds.php b/classes/feeds.php
index 37ce77aa9..a063b9ed5 100755
--- a/classes/feeds.php
+++ b/classes/feeds.php
@@ -1749,11 +1749,11 @@ class Feeds extends Handler_Protected {
 			}
 
 			if (!$allow_archived) {
-				$from_qpart = "${ext_tables_part}ttrss_entries LEFT JOIN ttrss_user_entries ON (ref_id = ttrss_entries.id), ttrss_feeds";
+				$from_qpart = "{$ext_tables_part}ttrss_entries LEFT JOIN ttrss_user_entries ON (ref_id = ttrss_entries.id), ttrss_feeds";
 				$feed_check_qpart = "ttrss_user_entries.feed_id = ttrss_feeds.id AND";
 
 			} else {
-				$from_qpart = "${ext_tables_part}ttrss_entries LEFT JOIN ttrss_user_entries ON (ref_id = ttrss_entries.id)
+				$from_qpart = "{$ext_tables_part}ttrss_entries LEFT JOIN ttrss_user_entries ON (ref_id = ttrss_entries.id)
 						LEFT JOIN ttrss_feeds ON (feed_id = ttrss_feeds.id)";
 				$feed_check_qpart = "";
 			}
@@ -2238,7 +2238,7 @@ class Feeds extends Handler_Protected {
 	 * @return array{0: string, 1: array<int, string>} [$search_query_part, $search_words]
 	 */
 	private static function _search_to_sql(string $search, string $search_language, int $owner_uid): array {
-		$keywords = str_getcsv(preg_replace('/(-?\w+)\:"(\w+)/', '"${1}:${2}', trim($search)), ' ');
+		$keywords = str_getcsv(preg_replace('/(-?\w+)\:"(\w+)/', '"{$1}:{$2}', trim($search)), ' ');
 		$query_keywords = array();
 		$search_words = array();
 		$search_query_leftover = array();
diff --git a/classes/pluginhandler.php b/classes/pluginhandler.php
index 5c73920e5..a6f0a4965 100644
--- a/classes/pluginhandler.php
+++ b/classes/pluginhandler.php
@@ -14,15 +14,15 @@ class PluginHandler extends Handler_Protected {
 				if (validate_csrf($csrf_token) || $plugin->csrf_ignore($method)) {
 					$plugin->$method();
 				} else {
-					user_error("Rejected ${plugin_name}->${method}(): invalid CSRF token.", E_USER_WARNING);
+					user_error("Rejected {$plugin_name}->{$method}(): invalid CSRF token.", E_USER_WARNING);
 					print Errors::to_json(Errors::E_UNAUTHORIZED);
 				}
 			} else {
-				user_error("Rejected ${plugin_name}->${method}(): unknown method.", E_USER_WARNING);
+				user_error("Rejected {$plugin_name}->{$method}(): unknown method.", E_USER_WARNING);
 				print Errors::to_json(Errors::E_UNKNOWN_METHOD);
 			}
 		} else {
-			user_error("Rejected ${plugin_name}->${method}(): unknown plugin.", E_USER_WARNING);
+			user_error("Rejected {$plugin_name}->{$method}(): unknown plugin.", E_USER_WARNING);
 			print Errors::to_json(Errors::E_UNKNOWN_PLUGIN);
 		}
 	}
diff --git a/classes/pref/labels.php b/classes/pref/labels.php
index a50a85a66..2e128691e 100644
--- a/classes/pref/labels.php
+++ b/classes/pref/labels.php
@@ -61,7 +61,7 @@ class Pref_Labels extends Handler_Protected {
 
 			if ($kind == "fg" || $kind == "bg") {
 				$sth = $this->pdo->prepare("UPDATE ttrss_labels2 SET
-					${kind}_color = ? WHERE id = ?
+					{$kind}_color = ? WHERE id = ?
 					AND owner_uid = ?");
 
 				$sth->execute([$color, $id, $_SESSION['uid']]);
diff --git a/classes/pref/prefs.php b/classes/pref/prefs.php
index 3285ce200..0c1b90213 100644
--- a/classes/pref/prefs.php
+++ b/classes/pref/prefs.php
@@ -240,7 +240,7 @@ class Pref_Prefs extends Handler_Protected {
 			$user->full_name = clean($_POST['full_name']);
 
 			if ($user->email != $new_email) {
-				Logger::log(E_USER_NOTICE, "Email address of user ".$user->login." has been changed to ${new_email}.");
+				Logger::log(E_USER_NOTICE, "Email address of user {$user->login} has been changed to {$new_email}.");
 
 				if ($user->email) {
 					$mailer = new Mailer();
diff --git a/lib/gettext/gettext.inc.php b/lib/gettext/gettext.inc.php
index ef36924c7..60a41ddfa 100644
--- a/lib/gettext/gettext.inc.php
+++ b/lib/gettext/gettext.inc.php
@@ -88,18 +88,18 @@ function get_list_of_locales($locale) {
       if ($modifier) {
         if ($country) {
           if ($charset)
-            array_push($locale_names, "${lang}_$country.$charset@$modifier");
-          array_push($locale_names, "${lang}_$country@$modifier");
+            array_push($locale_names, "{$lang}_$country.$charset@$modifier");
+          array_push($locale_names, "{$lang}_$country@$modifier");
         } elseif ($charset)
-            array_push($locale_names, "${lang}.$charset@$modifier");
+            array_push($locale_names, "{$lang}.$charset@$modifier");
         array_push($locale_names, "$lang@$modifier");
       }
       if ($country) {
         if ($charset)
-          array_push($locale_names, "${lang}_$country.$charset");
-        array_push($locale_names, "${lang}_$country");
+          array_push($locale_names, "{$lang}_$country.$charset");
+        array_push($locale_names, "{$lang}_$country");
       } elseif ($charset)
-          array_push($locale_names, "${lang}.$charset");
+          array_push($locale_names, "{$lang}.$charset");
       array_push($locale_names, $lang);
     }