diff --git a/newlib/libc/sys/arm/crt0.S b/newlib/libc/sys/arm/crt0.S
index 64d425900..8c9f7be38 100644
--- a/newlib/libc/sys/arm/crt0.S
+++ b/newlib/libc/sys/arm/crt0.S
@@ -85,7 +85,7 @@
 
 	/*  Stack limit is at end of data.  */
 	/*  Allow slop for stack overflow handling and small frames.  */
-#ifdef __ARM_ARCH_6M__
+#ifdef THUMB1_ONLY
 	ldr	r0, .LC2
 	adds	r0, #128
 	adds	r0, #128
@@ -137,7 +137,7 @@
 	beq	.LC27
 
 	/*  Allow slop for stack overflow handling and small frames.  */
-#ifdef __ARM_ARCH_6M__
+#ifdef THUMB1_ONLY
 	adds	r2, #128
 	adds	r2, #128
 	mov	sl, r2
@@ -164,7 +164,7 @@
 #ifdef __thumb2__
 	it	eq
 #endif	
-#ifdef __ARM_ARCH_6M__
+#ifdef THUMB1_ONLY
 	bne	.LC28
 	ldr	r3, .LC0
 .LC28:
@@ -219,7 +219,7 @@
 	   this default 64k is enough for the program being executed.
 	   However, it ensures that this simple crt0 world will not
 	   immediately cause an overflow event:  */
-#ifdef __ARM_ARCH_6M__
+#ifdef THUMB1_ONLY
 	movs	r2, #64
 	lsls	r2, r2, #10
 	subs	r2, r3, r2