diff --git a/vm/Config.macosx b/vm/Config.macosx
index 07629f72bb..d989a439be 100644
--- a/vm/Config.macosx
+++ b/vm/Config.macosx
@@ -1,5 +1,5 @@
 include vm/Config.unix
-CFLAGS += -fPIC
+CFLAGS += -fPIC -D_XOPEN_SOURCE
 
 PLAF_DLL_OBJS += vm/os-macosx.o vm/mach_signal.o
 
diff --git a/vm/Config.macosx.x86.32 b/vm/Config.macosx.x86.32
index 5c0d4e0ede..f983fff32b 100644
--- a/vm/Config.macosx.x86.32
+++ b/vm/Config.macosx.x86.32
@@ -1,2 +1,3 @@
 include vm/Config.macosx
 include vm/Config.x86.32
+CFLAGS += -m32