diff --git a/ChangeLog b/ChangeLog
index caf1309..aef4d6a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,6 +4,8 @@
 Changes
    * Introduced POLARSSL_HAVE_READDIR_R for systems without it
    * Improvements to the CMake build system, contributed by Julian Ospald.
+   * Work around a bug of the version of Clang shipped by Apple with Mavericks
+     that prevented bignum.c from compiling. (Reported by Rafael Baptista.)
 
 Security
    * Forbid change of server certificate during renegotiation to prevent
diff --git a/library/bignum.c b/library/bignum.c
index 5460290..0d13cd8 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -1114,7 +1114,14 @@
             Z.p[i - t - 1] = ~0;
         else
         {
-#if defined(POLARSSL_HAVE_UDBL)
+            /*
+             * The version of Clang shipped by Apple with Mavericks can't
+             * handle 128-bit division properly. Disable 128-bits division
+             * for Clang on Apple for now, while waiting for more input on the
+             * exact version(s) affected and their identification macros.
+             */
+#if defined(POLARSSL_HAVE_UDBL) && \
+    ! ( defined(__x86_64__) && defined(__clang__) && defined(__APPLE__) )
             t_udbl r;
 
             r  = (t_udbl) X.p[i] << biL;