diff --git a/plat/cpm/libsys/brk.c b/plat/cpm/libsys/brk.c
index 0b83b2523..6c139dd2a 100644
--- a/plat/cpm/libsys/brk.c
+++ b/plat/cpm/libsys/brk.c
@@ -31,13 +31,25 @@ int brk(void* newend)
 void* sbrk(int increment)
 {
 	char* old;
+	char* new;
 	
 	if (increment == 0)
 		return current;
 		
 	old = current;
-	if (brk(old + increment) < 0)
-		return OUT_OF_MEMORY;
-		
+	new = old + increment;
+
+	if ((increment > 0) && (new <= old))
+		goto out_of_memory;
+	else if ((increment < 0) && (new >= old))
+		goto out_of_memory;
+
+	if (brk(new) < 0)
+		goto out_of_memory;
+
 	return old;
+
+out_of_memory:
+	errno = ENOMEM;
+	return OUT_OF_MEMORY;
 }