diff --git a/src/system/linux/alloc.c b/src/system/linux/alloc.c
index 6c16dde..dd211bc 100644
--- a/src/system/linux/alloc.c
+++ b/src/system/linux/alloc.c
@@ -16,7 +16,7 @@ struct msh_linux_block_t {
   msh_linux_block *next;
   unsigned char free;
 };
-#define MSH_BLOCK_SIZE 21
+#define MSH_BLOCK_SIZE sizeof(struct msh_linux_block_t)
 
 static msh_linux_block *msh_linux_base = 0;
 
diff --git a/src/system/linux/i386.s b/src/system/linux/i386.s
index aa40fe5..a65b44d 100644
--- a/src/system/linux/i386.s
+++ b/src/system/linux/i386.s
@@ -7,7 +7,7 @@
 .globl syscall_6
 syscall_0:
     push %ebx
-    mov 0x4(%esp), %eax
+    mov 0x8(%esp), %eax
     int $0x80
     pop %ebx
     ret