Index: src/OFMutableString.m
==================================================================
--- src/OFMutableString.m
+++ src/OFMutableString.m
@@ -256,13 +256,12 @@
 	if (fmt == NULL)
 		@throw [OFInvalidFormatException newWithClass: isa];
 
 	if ((vasprintf(&t, [fmt cString], args)) == -1)
 		/*
-		 * This is only the most likely error to happen.
-		 * Unfortunately, as errno isn't always thread-safe, there's
-		 * no good way for us to find out what really happened.
+		 * This is only the most likely error to happen. Unfortunately,
+		 * there is no good way to check what really happened.
 		 */
 		@throw [OFOutOfMemoryException newWithClass: isa];
 
 	@try {
 		[self appendCString: t];

Index: src/OFString.m
==================================================================
--- src/OFString.m
+++ src/OFString.m
@@ -463,11 +463,16 @@
 	}
 
 	if ((t = vasprintf(&string, [fmt cString], args)) == -1) {
 		c = isa;
 		[super dealloc];
-		@throw [OFInitializationFailedException newWithClass: c];
+
+		/*
+		 * This is only the most likely error to happen. Unfortunately,
+		 * there is no good way to check what really happened.
+		 */
+		@throw [OFOutOfMemoryException newWithClass: c];
 	}
 	length = t;
 
 	switch (of_string_check_utf8(string, length)) {
 		case 1: