diff --git a/linux-user/m68k-sim.c b/linux-user/m68k-sim.c
index aab82dd7ec54fda6383df3c7e81485217246d85a..61c2468752393a0b53dfe093980659e043972b63 100644
--- a/linux-user/m68k-sim.c
+++ b/linux-user/m68k-sim.c
@@ -129,7 +129,7 @@ void do_m68k_simcall(CPUM68KState *env, int nr)
         {
             int32_t ret;
 
-            ret = do_brk((void *)ARG(0));
+            ret = do_brk((abi_ulong)ARG(0));
             if (ret == -ENOMEM)
                 ret = -1;
             check_err(env, ret);