diff --git a/conts/posix/test0/src/mmaptest.c b/conts/posix/test0/src/mmaptest.c
index 5ff6230..b6e82ec 100644
--- a/conts/posix/test0/src/mmaptest.c
+++ b/conts/posix/test0/src/mmaptest.c
@@ -33,7 +33,7 @@ int mmaptest(void)
 	if (write(fd, &x, sizeof(x)) < 0)
 		goto out_err;
 
-	if ((int)(base = mmap(0, PAGE_SIZE*16, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)) < 0)
+	if (IS_ERR(base = mmap(0, PAGE_SIZE*16, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)))
 		goto out_err;
 
 	*(unsigned int *)(base + PAGE_SIZE*2) = 0x1000;
diff --git a/conts/posix/test0/src/mutextest.c b/conts/posix/test0/src/mutextest.c
index 60669fd..d4f4574 100644
--- a/conts/posix/test0/src/mutextest.c
+++ b/conts/posix/test0/src/mutextest.c
@@ -49,8 +49,8 @@ int user_mutex_test(void)
 	 * Create a shared anonymous memory region. This can be
 	 * accessed by both parent and child after a fork.
 	 */
-	if ((int)(base = mmap(0, map_size, PROT_READ | PROT_WRITE,
-			      MAP_SHARED | MAP_ANONYMOUS, 0, 0)) < 0) {
+	if (IS_ERR(base = mmap(0, map_size, PROT_READ | PROT_WRITE,
+			      MAP_SHARED | MAP_ANONYMOUS, 0, 0))) {
 		printf("%s: mmap for extended ipc buffer failed: %x\n",
 			    __FUNCTION__, (int)base);
 		goto out_err;