diff --git a/Source/CString.m b/Source/CString.m
index 067b5b402..ecf49d377 100644
--- a/Source/CString.m
+++ b/Source/CString.m
@@ -29,7 +29,7 @@
 @implementation CString
 
 /* This is the designated initializer for this class */
-- initWithCString: (char*)aCharPtr range: (IndexRange)aRange
+- initWithCString: (const char*)aCharPtr range: (IndexRange)aRange
 {
   [super initWithType:@encode(char)];
   _count = aRange.length;