diff --git a/demo.php b/demo.php
index f2d865e..aa0c328 100644
--- a/demo.php
+++ b/demo.php
@@ -70,7 +70,7 @@ public function __construct()
         'demo.log'
     ]);
 
-    echo "Logging to ${logFile}\n";
+    echo "Logging to {$logFile}\n";
 
     LoggerFactory::setup((new MonologLoggerFactory())
         ->setDefaultHandlers([
diff --git a/src/Rox/Core/CustomProperties/DeviceProperty.php b/src/Rox/Core/CustomProperties/DeviceProperty.php
index 69f7054..2aaf77e 100644
--- a/src/Rox/Core/CustomProperties/DeviceProperty.php
+++ b/src/Rox/Core/CustomProperties/DeviceProperty.php
@@ -7,6 +7,6 @@ class DeviceProperty extends CustomProperty
     public function getName()
     {
         $name = parent::getName();
-        return "rox.${name}";
+        return "rox.{$name}";
     }
 }
diff --git a/src/Rox/Core/Entities/RoxStringBase.php b/src/Rox/Core/Entities/RoxStringBase.php
index ce71a58..4e7338f 100644
--- a/src/Rox/Core/Entities/RoxStringBase.php
+++ b/src/Rox/Core/Entities/RoxStringBase.php
@@ -90,7 +90,7 @@ protected function checkValueType($value)
     {
         $converter = $this->getConverter();
         if (!$converter->isValid($value)) {
-            throw new InvalidArgumentException("Invalid value type: ${value}");
+            throw new InvalidArgumentException("Invalid value type: {$value}");
         }
         return $converter->convertToString($value);
     }
@@ -107,7 +107,7 @@ protected function checkVariationsType(array $variations)
             return !$converter->isValid($value);
         })) {
             $invalidValue = array_shift($invalidVariations);
-            throw new InvalidArgumentException("Invalid variation type: ${invalidValue}");
+            throw new InvalidArgumentException("Invalid variation type: {$invalidValue}");
         }
         return array_map(function ($v) use ($converter) {
             return $converter->convertToString($v);
diff --git a/src/Rox/Core/Network/GuzzleHttpClient.php b/src/Rox/Core/Network/GuzzleHttpClient.php
index dd4e732..c511149 100644
--- a/src/Rox/Core/Network/GuzzleHttpClient.php
+++ b/src/Rox/Core/Network/GuzzleHttpClient.php
@@ -128,7 +128,7 @@ function postJson($uri, array $data)
                 RequestOptions::TIMEOUT => $this->_timeout,
             ]));
         } catch (GuzzleException $e) {
-            $this->_log->error("Failed to send data to ${uri}: {$e->getMessage()}", [
+            $this->_log->error("Failed to send data to {$uri}: {$e->getMessage()}", [
                 'exception' => $e
             ]);
             return new HttpErrorResponse($e->getCode(), $e->getMessage());
@@ -142,7 +142,7 @@ function postJson($uri, array $data)
      */
     private function _handleError($uri, GuzzleException $e)
     {
-        $this->_log->error("Failed to send data to ${uri}: {$e->getMessage()}", [
+        $this->_log->error("Failed to send data to {$uri}: {$e->getMessage()}", [
             'exception' => $e
         ]);
         return new HttpErrorResponse($e->getCode(), $e->getMessage());
diff --git a/src/Rox/Core/Register/Registerer.php b/src/Rox/Core/Register/Registerer.php
index f3f1ee1..fa5aefd 100644
--- a/src/Rox/Core/Register/Registerer.php
+++ b/src/Rox/Core/Register/Registerer.php
@@ -65,17 +65,17 @@ public function registerInstance($container, $ns)
             }
         } catch (ReflectionException $e) {
             $type = get_class($container);
-            $this->_log->error("Failed to obtain properties of class ${type}", [
+            $this->_log->error("Failed to obtain properties of class {$type}", [
                 'exception' => $e
             ]);
             throw new RuntimeException(
-                "Failed to obtain properties of class ${type}. See inner exception for details.", 0, $e);
+                "Failed to obtain properties of class {$type}. See inner exception for details.", 0, $e);
         }
 
         foreach ($properties as $name => $value) {
             if ($value instanceof RoxStringBase) {
                 if ($ns) {
-                    $name = "${ns}.${name}";
+                    $name = "{$ns}.{$name}";
                 }
                 $this->_flagRepository->addFlag($value, $name);
             }
diff --git a/src/Rox/Core/Roxx/ExperimentsExtensions.php b/src/Rox/Core/Roxx/ExperimentsExtensions.php
index be95241..e2e026a 100644
--- a/src/Rox/Core/Roxx/ExperimentsExtensions.php
+++ b/src/Rox/Core/Roxx/ExperimentsExtensions.php
@@ -54,7 +54,7 @@ public function extend()
         $this->_parser->addOperator("mergeSeed", function (ParserInterface $parser, StackInterface $stack, ContextInterface $context) {
             $seed1 = (string)$stack->pop();
             $seed2 = (string)$stack->pop();
-            $stack->push("${seed1}.${seed2}");
+            $stack->push("{$seed1}.{$seed2}");
         });
 
         $this->_parser->addOperator("isInPercentage", function (ParserInterface $parser, StackInterface $stack, ContextInterface $context) {
diff --git a/src/Rox/Core/Roxx/Parser.php b/src/Rox/Core/Roxx/Parser.php
index d95248e..8667038 100644
--- a/src/Rox/Core/Roxx/Parser.php
+++ b/src/Rox/Core/Roxx/Parser.php
@@ -285,7 +285,7 @@ public function evaluateExpression($expression, $context = null, $evaluationCont
 
         } catch (Exception $exception) {
 
-            $this->_log->warning("Roxx Exception: Failed evaluate expression ${expression}", [
+            $this->_log->warning("Roxx Exception: Failed evaluate expression {$expression}", [
                 'exception' => $exception
             ]);
         }
diff --git a/src/Rox/Core/Roxx/RegularExpressionExtensions.php b/src/Rox/Core/Roxx/RegularExpressionExtensions.php
index 92b9927..32ee9f0 100644
--- a/src/Rox/Core/Roxx/RegularExpressionExtensions.php
+++ b/src/Rox/Core/Roxx/RegularExpressionExtensions.php
@@ -58,11 +58,11 @@ function (ParserInterface $parser, StackInterface $stack, ContextInterface $cont
                     }
 
                     if ($flag == 'n') {
-                        $this->_log->warning("Regexp flag ${flag} is not supported.");
+                        $this->_log->warning("Regexp flag {$flag} is not supported.");
                     }
                 }
 
-                $stack->push(preg_match("/${pattern}/${filteredFlags}", $str) === 1);
+                $stack->push(preg_match("/{$pattern}/{$filteredFlags}", $str) === 1);
             });
     }
 }
diff --git a/src/Rox/Core/XPack/Analytics/AnalyticsClient.php b/src/Rox/Core/XPack/Analytics/AnalyticsClient.php
index 8839449..6382be9 100644
--- a/src/Rox/Core/XPack/Analytics/AnalyticsClient.php
+++ b/src/Rox/Core/XPack/Analytics/AnalyticsClient.php
@@ -117,7 +117,7 @@ private function _flushBatch(array $messages)
         if (200 == $statusCode) {
             return true;
         }
-        $this->_log->error("Failed to post data to ${url}: HTTP response code ${statusCode} ({$response->getContent()->readAsString()})");
+        $this->_log->error("Failed to post data to {$url}: HTTP response code {$statusCode} ({$response->getContent()->readAsString()})");
 
         return false;
     }
diff --git a/src/Rox/Core/XPack/Security/XSignatureVerifier.php b/src/Rox/Core/XPack/Security/XSignatureVerifier.php
index 8132255..c1ddf05 100644
--- a/src/Rox/Core/XPack/Security/XSignatureVerifier.php
+++ b/src/Rox/Core/XPack/Security/XSignatureVerifier.php
@@ -17,7 +17,7 @@ function verify($data, $signatureBase64)
             return true;
         }
         $cert = chunk_split(self::ROXCertificateBase64);
-        $publicKey = openssl_pkey_get_public("-----BEGIN CERTIFICATE-----\n${cert}-----END CERTIFICATE-----");
+        $publicKey = openssl_pkey_get_public("-----BEGIN CERTIFICATE-----\n{$cert}-----END CERTIFICATE-----");
         $signature = base64_decode($signatureBase64);
         return openssl_verify($data, $signature, $publicKey, OPENSSL_ALGO_SHA256) === 1;
     }