diff --git a/src/runtime/Config.x86-darwin b/src/runtime/Config.x86-darwin
index 8c70575..ff19612 100644
--- a/src/runtime/Config.x86-darwin
+++ b/src/runtime/Config.x86-darwin
@@ -9,8 +9,8 @@
 # provided with absolutely no warranty. See the COPYING and CREDITS
 # files for more information.
 
-CFLAGS = -g -Wall -O2 -fdollars-in-identifiers -mmacosx-version-min=10.4
-LINKFLAGS += -mmacosx-version-min=10.4
+CFLAGS = -arch i386 -g -Wall -O2 -fdollars-in-identifiers -mmacosx-version-min=10.4
+LINKFLAGS += -arch i386 -mmacosx-version-min=10.4
 OS_SRC = bsd-os.c x86-bsd-os.c darwin-os.c x86-darwin-os.c darwin-dlshim.c darwin-langinfo.c
 OS_LIBS = -lSystem -lc -ldl
 ifdef LISP_FEATURE_SB_THREAD
diff --git a/src/runtime/darwin-os.c b/src/runtime/darwin-os.c
index 45738df..a60dc30 100644
--- a/src/runtime/darwin-os.c
+++ b/src/runtime/darwin-os.c
@@ -18,7 +18,6 @@
 #include "globals.h"
 #include "runtime.h"
 #include <signal.h>
-#include <ucontext.h>
 #include <limits.h>
 #include <mach-o/dyld.h>
 #include "bsd-os.h"