diff --git a/Foundation/NSDecimal.swift b/Foundation/NSDecimal.swift
index c6e0961..dcba6f4 100644
--- a/Foundation/NSDecimal.swift
+++ b/Foundation/NSDecimal.swift
@@ -1412,7 +1412,7 @@
 
 public func NSDecimalString(_ dcm: UnsafePointer<Decimal>, _ locale: AnyObject?) -> String {
     guard locale == nil else {
-        fatalError("Locale not supported: \(locale)")
+        fatalError("Locale not supported: \(locale!)")
     }
     return dcm.pointee.description
 }