diff --git a/tracker/core/file_api.php b/core/file_api.php
index 06ebc5a1a4..2e663534d5 100644
--- a/core/file_api.php
+++ b/core/file_api.php
@@ -710,7 +710,7 @@ function diskfile_is_name_unique( $p_name, $p_filepath ) {
  * @return boolean true if unique
  */
 function file_is_name_unique( $p_name, $p_bug_id, $p_table = 'bug' ) {
-       $t_file_table = db_get_table( "${p_table}_file" );
+       $t_file_table = db_get_table( "{$p_table}_file" );
 
        db_param_push();
        $t_query = 'SELECT COUNT(*) FROM ' . $t_file_table . ' WHERE filename=' . db_param();
diff --git a/core/plugin_api.php b/core/plugin_api.php
index eda53f62ff..8b85e134c7 100644
--- a/core/plugin_api.php
+++ b/core/plugin_api.php
@@ -420,7 +420,7 @@ function plugin_error( $p_error_name, $p_error_type = ERROR, $p_basename = null
                $t_basename = $p_basename;
        }
 
-       $t_error_code = "plugin_${t_basename}_${p_error_name}";
+       $t_error_code = "plugin_{$t_basename}_{$p_error_name}";
 
        trigger_error( $t_error_code, $p_error_type );
 }
@@ -1030,7 +1030,7 @@ function plugin_init( $p_basename ) {
                $t_plugin_errors = $t_plugin->errors();
 
                foreach( $t_plugin_errors as $t_error_name => $t_error_string ) {
-                       $t_error_code = "plugin_${p_basename}_${t_error_name}";
+                       $t_error_code = "plugin_{$p_basename}_{$t_error_name}";
                        $g_lang_strings[$t_lang]['MANTIS_ERROR'][$t_error_code] = $t_error_string;
                }
 
diff --git a/core/string_api.php b/core/string_api.php
index e14a652d4c..f0da6db6c8 100644
--- a/core/string_api.php
+++ b/core/string_api.php
@@ -492,15 +492,15 @@ function string_insert_hrefs( $p_string ) {
 
                # valid set of characters that may occur in url scheme. Note: - should be first (A-F != -AF).
                $t_url_valid_chars       = '-_.,!~*\';\/?%^\\\\:@&={\|}+$#[:alnum:]\pL';
-               $t_url_chars             = "(?:${t_url_hex}|[${t_url_valid_chars}\(\)\[\]])";
-               $t_url_chars2            = "(?:${t_url_hex}|[${t_url_valid_chars}])";
-               $t_url_chars_in_brackets = "(?:${t_url_hex}|[${t_url_valid_chars}\(\)])";
-               $t_url_chars_in_parens   = "(?:${t_url_hex}|[${t_url_valid_chars}\[\]])";
+               $t_url_chars             = "(?:{$t_url_hex}|[{$t_url_valid_chars}\(\)\[\]])";
+               $t_url_chars2            = "(?:{$t_url_hex}|[{$t_url_valid_chars}])";
+               $t_url_chars_in_brackets = "(?:{$t_url_hex}|[{$t_url_valid_chars}\(\)])";
+               $t_url_chars_in_parens   = "(?:{$t_url_hex}|[{$t_url_valid_chars}\[\]])";
 
                $t_url_part1 = $t_url_chars;
-               $t_url_part2 = "(?:\(${t_url_chars_in_parens}*\)|\[${t_url_chars_in_brackets}*\]|${t_url_chars2})";
+               $t_url_part2 = "(?:\({$t_url_chars_in_parens}*\)|\[{$t_url_chars_in_brackets}*\]|{$t_url_chars2})";
 
-               $s_url_regex = "/(${t_url_protocol}(${t_url_part1}*?${t_url_part2}+))/su";
+               $s_url_regex = "/({$t_url_protocol}({$t_url_part1}*?{$t_url_part2}+))/su";
 
                # e-mail regex
                $s_email_regex = substr_replace( email_regex_simple(), '(?:mailto:)?', 1, 0 );
@@ -516,7 +516,7 @@ function string_insert_hrefs( $p_string ) {
                        } else {
                                $t_url_target = '';
                        }
-                       return "<a ${t_url_href}${t_url_target}>${p_match[1]}</a>";
+                       return "<a {$t_url_href}{$t_url_target}>{$p_match[1]}</a>";
                },
                $p_string
        );
diff --git a/login_page.php b/login_page.php
index 69830ba051..a08f7619a8 100644
--- a/login_page.php
+++ b/login_page.php
@@ -165,7 +165,7 @@ if( config_get_global( 'admin_checks' ) == ON ) {
        function debug_setting_message ( $p_type, $p_setting, $p_value ) {
                return sprintf( lang_get( 'warning_change_setting' ), $p_setting, $p_value )
                        . sprintf( lang_get( 'word_separator' ) )
-                       . sprintf( lang_get( "warning_${p_type}_hazard" ) );
+                       . sprintf( lang_get( "warning_{$p_type}_hazard" ) );
        }
 
        $t_config = 'show_detailed_errors';