https://bugs.webkit.org/show_bug.cgi?id=157554

--- a/Source/WTF/wtf/OSRandomSource.cpp
+++ b/Source/WTF/wtf/OSRandomSource.cpp
@@ -29,7 +29,7 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-#if !OS(DARWIN) && OS(UNIX)
+#if OS(UNIX) && !(OS(DARWIN) && __MAC_OS_X_VERSION_MIN_REQUIRED >= 1070)
 #include <errno.h>
 #include <fcntl.h>
 #include <unistd.h>
@@ -46,7 +46,7 @@
 
 namespace WTF {
 
-#if !OS(DARWIN) && OS(UNIX)
+#if OS(UNIX) && !(OS(DARWIN) && __MAC_OS_X_VERSION_MIN_REQUIRED >= 1070)
 NEVER_INLINE NO_RETURN_DUE_TO_CRASH static void crashUnableToOpenURandom()
 {
     CRASH();
@@ -60,8 +56,8 @@ NEVER_INLINE NO_RETURN_DUE_TO_CRASH static void crashUnableToReadFromURandom()
     
 void cryptographicallyRandomValuesFromOS(unsigned char* buffer, size_t length)
 {
-#if OS(DARWIN)
-    RELEASE_ASSERT(!CCRandomCopyBytes(kCCRandomDefault, buffer, length));
+#if OS(DARWIN) && __MAC_OS_X_VERSION_MIN_REQUIRED >= 1070
+    return arc4random_buf(buffer, length);
 #elif OS(UNIX)
     int fd = open("/dev/urandom", O_RDONLY, 0);
     if (fd < 0)