diff --git a/arch/arm/mach-imx/iomux-imx31.c b/arch/arm/mach-imx/iomux-imx31.c
index d6a30753ca7c..6dd22cabf4d3 100644
--- a/arch/arm/mach-imx/iomux-imx31.c
+++ b/arch/arm/mach-imx/iomux-imx31.c
@@ -40,7 +40,7 @@ static DEFINE_SPINLOCK(gpio_mux_lock);
 
 #define IOMUX_REG_MASK (IOMUX_PADNUM_MASK & ~0x3)
 
-static unsigned long mxc_pin_alloc_map[NB_PORTS * 32 / BITS_PER_LONG];
+static DECLARE_BITMAP(mxc_pin_alloc_map, NB_PORTS * 32);
 /*
  * set the mode for a IOMUX pin.
  */