diff --git a/api/String.cpp b/api/String.cpp
index 5eb0b2a2..b27a5013 100644
--- a/api/String.cpp
+++ b/api/String.cpp
@@ -123,7 +123,7 @@ String::String(double value, unsigned char decimalPlaces)
 
 String::~String()
 {
-	free(buffer);
+	if (buffer) free(buffer);
 }
 
 /*********************************************/