diff --git a/core/mem.h b/core/mem.h
index 278c930..216fbb8 100644
--- a/core/mem.h
+++ b/core/mem.h
@@ -11,8 +11,8 @@
 
 
 // Defined in linker.ld script
-extern uint32_t __ld_kernel_begin;
-extern uint32_t __ld_kernel_end;
+extern char  __ld_kernel_begin;
+extern char  __ld_kernel_end;
 
 struct phyMemDesc {
     paddr_t phy_addr;