1 files changed, 4 insertions, 3 deletions

diff --git a/arch/i386/boot/apm.c b/arch/i386/boot/apm.c
index a34087c370c0..eab50c55a3a5 100644
--- a/arch/i386/boot/apm.c
+++ b/arch/i386/boot/apm.c
@@ -40,14 +40,15 @@ int query_apm_bios(void)
         if (bx != 0x504d)       /* "PM" signature */
                 return -1;
 
-        if (cx & 0x02)          /* 32 bits supported? */
+        if (!(cx & 0x02))               /* 32 bits supported? */
                 return -1;
 
         /* Disconnect first, just in case */
         ax = 0x5304;
+        bx = 0;
         asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp"
-                     : "+a" (ax)
-                     : : "ebx", "ecx", "edx", "esi", "edi");
+                     : "+a" (ax), "+b" (bx)
+                     : : "ecx", "edx", "esi", "edi");
 
         /* Paranoia */
         ebx = esi = 0;