diff --git a/include/asm-x86/io.h b/include/asm-x86/io.h
index bf5d629b3a39..a145210ac16b 100644
--- a/include/asm-x86/io.h
+++ b/include/asm-x86/io.h
@@ -73,6 +73,8 @@ build_mmio_write(__writeq, "q", unsigned long, "r", )
 #define writeq writeq
 #endif
 
+extern int iommu_bio_merge;
+
 #ifdef CONFIG_X86_32
 # include "io_32.h"
 #else
diff --git a/include/asm-x86/io_64.h b/include/asm-x86/io_64.h
index ddd8058a5026..1e271378afaf 100644
--- a/include/asm-x86/io_64.h
+++ b/include/asm-x86/io_64.h
@@ -233,7 +233,6 @@ void memset_io(volatile void __iomem *a, int b, size_t c);
 
 #define flush_write_buffers()
 
-extern int iommu_bio_merge;
 #define BIO_VMERGE_BOUNDARY iommu_bio_merge
 
 /*