Index: src/X509Certificate.m
==================================================================
--- src/X509Certificate.m
+++ src/X509Certificate.m
@@ -34,10 +34,12 @@
 #import <ObjFW/OFInitializationFailedException.h>
 #import <ObjFW/OFInvalidEncodingException.h>
 #import <ObjFW/OFList.h>
 #import <ObjFW/OFMutableDictionary.h>
 #import <ObjFW/OFString.h>
+
+#import <ObjFW/macros.h>
 
 @implementation X509Certificate
 - initWithFile: (OFString*)file
 {
 	self = [self init];
@@ -343,12 +345,12 @@
 		return NO;
 
 	asserted = [asserted substringWithRange:
 	    of_range(2, [asserted length] - 2)];
 
-	firstDot = [domain indexOfFirstOccurrenceOfString: @"."];
-	if (firstDot == OF_INVALID_INDEX)
+	firstDot = [domain rangeOfString: @"."].location;
+	if (firstDot == OF_NOT_FOUND)
 		return NO;
 
 	domain = [domain substringWithRange:
 	    of_range(firstDot + 1, [domain length] - firstDot - 1)];