diff --git a/OPTYap/opt.proto.h b/OPTYap/opt.proto.h
index b954016dc..971a5b40b 100644
--- a/OPTYap/opt.proto.h
+++ b/OPTYap/opt.proto.h
@@ -80,7 +80,7 @@ void resume_suspension_frame(susp_fr_ptr, or_fr_ptr);
 
 #ifdef YAPOR
 void Yap_init_yapor_global_local_memory(void);
-void Yap_init_yapor_stacks_memory(long, long, long, int);
+void Yap_init_yapor_stacks_memory(UInt, UInt, UInt, int);
 void Yap_unmap_yapor_memory(void);
 void Yap_remap_yapor_memory(void);
 #endif /* YAPOR */
diff --git a/OPTYap/or.memory.c b/OPTYap/or.memory.c
index 17c05b91a..1edf2c89d 100644
--- a/OPTYap/or.memory.c
+++ b/OPTYap/or.memory.c
@@ -83,7 +83,7 @@ void Yap_init_yapor_global_local_memory(void) {
 }
 
 
-void Yap_init_yapor_stacks_memory(long TrailStackArea, long HeapStackArea, long GlobalLocalStackArea, int n_workers) {
+void Yap_init_yapor_stacks_memory(UInt TrailStackArea, UInt HeapStackArea, UInt GlobalLocalStackArea, int n_workers) {
   long StacksArea;
 
   TrailStackArea = ADJUST_SIZE_TO_PAGE(TrailStackArea);