diff --git a/arch/arm/mach-s3c2410/clock.c b/arch/arm/mach-s3c2410/clock.c
index f596082..8b3d5dc 100644
--- a/arch/arm/mach-s3c2410/clock.c
+++ b/arch/arm/mach-s3c2410/clock.c
@@ -98,7 +98,10 @@
 	struct clk *clk = ERR_PTR(-ENOENT);
 	int idno;
 
-	idno = (dev == NULL) ? -1 : to_platform_device(dev)->id;
+	if (dev == NULL || dev->bus != &platform_bus_type)
+		idno = -1;
+	else
+		idno = to_platform_device(dev)->id;
 
 	down(&clocks_sem);