diff --git a/arch/arm/plat-pxa/mfp.c b/arch/arm/plat-pxa/mfp.c
index 9405d0379c85..be58f9fe65b0 100644
--- a/arch/arm/plat-pxa/mfp.c
+++ b/arch/arm/plat-pxa/mfp.c
@@ -207,7 +207,7 @@ unsigned long mfp_read(int mfp)
 {
 	unsigned long val, flags;
 
-	BUG_ON(mfp >= MFP_PIN_MAX);
+	BUG_ON(mfp < 0 || mfp >= MFP_PIN_MAX);
 
 	spin_lock_irqsave(&mfp_spin_lock, flags);
 	val = mfpr_readl(mfp_table[mfp].mfpr_off);
@@ -220,7 +220,7 @@ void mfp_write(int mfp, unsigned long val)
 {
 	unsigned long flags;
 
-	BUG_ON(mfp >= MFP_PIN_MAX);
+	BUG_ON(mfp < 0 || mfp >= MFP_PIN_MAX);
 
 	spin_lock_irqsave(&mfp_spin_lock, flags);
 	mfpr_writel(mfp_table[mfp].mfpr_off, val);