diff --git a/configure/os/CONFIG.darwin-x86.Common b/configure/os/CONFIG.darwin-x86.Common
index 960c74b8a..e779f7dc1 100644
--- a/configure/os/CONFIG.darwin-x86.Common
+++ b/configure/os/CONFIG.darwin-x86.Common
@@ -3,7 +3,6 @@
 # Definitions for darwin-x86 host builds
 # Sites may override these definitions in CONFIG_SITE.darwin-x86.Common
 #-------------------------------------------------------
-#support for IPv6 etc.
-OP_SYS_CFLAGS += -DHAVE_SOCKADDR_SA_LEN=1
+
 #Include definitions common to unix hosts
 include $(CONFIG)/os/CONFIG.UnixCommon.Common
diff --git a/configure/os/CONFIG.darwinCommon.darwinCommon b/configure/os/CONFIG.darwinCommon.darwinCommon
index bfd61830d..5575eb35f 100644
--- a/configure/os/CONFIG.darwinCommon.darwinCommon
+++ b/configure/os/CONFIG.darwinCommon.darwinCommon
@@ -30,8 +30,10 @@ ARCH_DEP_LDFLAGS += $(ARCH_DEP_FLAGS)
 #
 # Special flags for Darwin
 #   No common blocks (as required when using shared libraries)
+#   OS provides socket address length
 #
 OP_SYS_CFLAGS += -fno-common
+OP_SYS_CFLAGS += -DHAVE_SOCKADDR_SA_LEN=1
 
 #
 # Darwin os definition