diff --git a/sys/powerpc/aim/aim_machdep.c b/sys/powerpc/aim/aim_machdep.c
index 835783f972ec..ab09ab6b5ad7 100644
--- a/sys/powerpc/aim/aim_machdep.c
+++ b/sys/powerpc/aim/aim_machdep.c
@@ -179,17 +179,6 @@ aim_cpu_init(vm_offset_t toc)
 	trap_offset = 0;
 	cacheline_warn = 0;
 
-	#ifdef __powerpc64__
-	/*
-	 * Switch to 64-bit mode, if the bootloader didn't, before we start 
-	 * using memory beyond what the bootloader might have set up.
-	 * Guaranteed not to cause an implicit branch since we either (a)
-	 * started with a 32-bit bootloader below 4 GB or (b) were already in
-	 * 64-bit mode, making this a no-op.
-	 */
-	mtmsrd(mfmsr() | PSL_SF);
-	#endif
-
 	/* Various very early CPU fix ups */
 	switch (mfpvr() >> 16) {
 		/*
diff --git a/sys/powerpc/aim/locore64.S b/sys/powerpc/aim/locore64.S
index cd64b5f81cf9..e7d27b53b430 100644
--- a/sys/powerpc/aim/locore64.S
+++ b/sys/powerpc/aim/locore64.S
@@ -76,6 +76,14 @@ btext:
  */
 	.text
 ASENTRY_NOPROF(__start)
+	/* Set 64-bit mode if not yet set before branching to C */
+	mfmsr	%r20
+	li	%r21,1
+	insrdi	%r20,%r21,1,0
+	mtmsrd	%r20
+	isync
+	nop	/* Make this block a multiple of 8 bytes */
+
 	/* Set up the TOC pointer */
 	b	0f
 	.align 3