diff --git a/src/kits/support/String.cpp b/src/kits/support/String.cpp
index 8fe546d28e..1f2ee6bd5f 100644
--- a/src/kits/support/String.cpp
+++ b/src/kits/support/String.cpp
@@ -1697,7 +1697,7 @@ BString::ReplaceCharsSet(const char* setOfChars, const char* with)
 	BString setString(setOfChars);
 	BString result;
 
-	int32 withLength = withLength;
+	int32 withLength = strlen(with);
 	int32 charCount = CountChars();
 	for (int32 i = 0; i < charCount; i++) {
 		int32 charLength;