diff --git a/phpstan.neon b/phpstan.neon
index 2d7efab..be84088 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -23,3 +23,4 @@ parameters:
             paths:
                 - src/Currency.php
         - identifier: missingType.iterableValue
+        - identifier: unset.possiblyHookedProperty
diff --git a/src/PriceFormatter.php b/src/PriceFormatter.php
index 67f0a19..cb2963c 100644
--- a/src/PriceFormatter.php
+++ b/src/PriceFormatter.php
@@ -44,7 +44,7 @@ class PriceFormatter
         $formatted = ltrim($formatted, $currency->prefix());
         $formatted = rtrim($formatted, $currency->suffix());
 
-        $removeNonDigits = preg_replace('/[^\d' . preg_quote($currency->decimalSeparator()) . ']/', '', $formatted);
+        $removeNonDigits = preg_replace('/[^\d' . preg_quote($currency->decimalSeparator(), '/') . ']/', '', $formatted);
 
         if (! is_string($removeNonDigits)) {
             throw new Exception('The formatted string could not be resolved to a valid number.');