diff --git a/Source/NSString.m b/Source/NSString.m
index f30fbf296..98930fe4a 100644
--- a/Source/NSString.m
+++ b/Source/NSString.m
@@ -33,6 +33,14 @@
 
 */
 
+/* xxx Temporarily set HAVE_REGISTER_PRINTF_FUNCTION function to 0
+   because I can't seem to figure out which versions of libc pass a
+   `va_list' to the output handler, and which pass a `void**' to the
+   output handler.  Once I figure this out, these lines should be
+   removed. */
+#undef HAVE_REGISTER_PRINTF_FUNCTION
+#define HAVE_REGISTER_PRINTF_FUNCTION 0
+
 #include <gnustep/base/preface.h>
 #include <gnustep/base/Coding.h>
 #include <Foundation/NSString.h>