diff --git a/sys/boot/i386/boot2/Makefile b/sys/boot/i386/boot2/Makefile
index ed3f9c28f01..3e23061df81 100644
--- a/sys/boot/i386/boot2/Makefile
+++ b/sys/boot/i386/boot2/Makefile
@@ -21,7 +21,9 @@ BOOT2_UFS?=	UFS1_AND_UFS2
 #BOOT2_UFS?=	UFS1_ONLY
 
 CFLAGS=	-Os \
-	-fno-guess-branch-probability -fomit-frame-pointer\
+	-fno-guess-branch-probability \
+	-fomit-frame-pointer \
+	-fno-unit-at-a-time \
 	-mno-align-long-strings \
 	-mrtd \
 	-D${BOOT2_UFS} \
diff --git a/sys/boot/i386/gptboot/Makefile b/sys/boot/i386/gptboot/Makefile
index ed3f9c28f01..3e23061df81 100644
--- a/sys/boot/i386/gptboot/Makefile
+++ b/sys/boot/i386/gptboot/Makefile
@@ -21,7 +21,9 @@ BOOT2_UFS?=	UFS1_AND_UFS2
 #BOOT2_UFS?=	UFS1_ONLY
 
 CFLAGS=	-Os \
-	-fno-guess-branch-probability -fomit-frame-pointer\
+	-fno-guess-branch-probability \
+	-fomit-frame-pointer \
+	-fno-unit-at-a-time \
 	-mno-align-long-strings \
 	-mrtd \
 	-D${BOOT2_UFS} \