diff --git a/vm/gc_info.cpp b/vm/gc_info.cpp
index 7c727aac0d..a693fc5455 100644
--- a/vm/gc_info.cpp
+++ b/vm/gc_info.cpp
@@ -13,7 +13,7 @@ cell gc_info::return_address_index(cell return_address)
 			return i;
 	}
 
-	return gc_info_missing_value;
+	return (cell)-1;
 }
 
 }
diff --git a/vm/gc_info.hpp b/vm/gc_info.hpp
index d6bb79f4bd..9bff88b9b2 100644
--- a/vm/gc_info.hpp
+++ b/vm/gc_info.hpp
@@ -1,8 +1,6 @@
 namespace factor
 {
 
-const cell gc_info_missing_value = (cell)-1;
-
 struct gc_info {
 	u32 scrub_d_count;
 	u32 scrub_r_count;
@@ -58,7 +56,7 @@ struct gc_info {
 			+ index * gc_root_count;
 	}
 
-	cell lookup_base_pointer(cell index, cell derived_root)
+	u32 lookup_base_pointer(cell index, cell derived_root)
 	{
 		return base_pointer_map()[index * derived_root_count + derived_root];
 	}
diff --git a/vm/slot_visitor.hpp b/vm/slot_visitor.hpp
index b97f988e65..b2dd40e582 100755
--- a/vm/slot_visitor.hpp
+++ b/vm/slot_visitor.hpp
@@ -293,7 +293,7 @@ struct call_frame_slot_visitor {
 
 		assert(return_address < compiled->size());
 		cell callsite = info->return_address_index(return_address);
-		if(callsite == gc_info_missing_value)
+		if(callsite == (cell)-1)
 			return;
 
 #ifdef DEBUG_GC_MAPS
@@ -305,8 +305,8 @@ struct call_frame_slot_visitor {
 		/* Subtract old value of base pointer from every derived pointer. */
 		for(cell spill_slot = 0; spill_slot < info->derived_root_count; spill_slot++)
 		{
-			cell base_pointer = info->lookup_base_pointer(callsite, spill_slot);
-			if(base_pointer != gc_info_missing_value)
+			u32 base_pointer = info->lookup_base_pointer(callsite, spill_slot);
+			if(base_pointer != (u32)-1)
 			{
 #ifdef DEBUG_GC_MAPS
 				std::cout << "visiting derived root " << spill_slot
@@ -334,8 +334,8 @@ struct call_frame_slot_visitor {
 		/* Add the base pointers to obtain new derived pointer values. */
 		for(cell spill_slot = 0; spill_slot < info->derived_root_count; spill_slot++)
 		{
-			cell base_pointer = info->lookup_base_pointer(callsite, spill_slot);
-			if(base_pointer != gc_info_missing_value)
+			u32 base_pointer = info->lookup_base_pointer(callsite, spill_slot);
+			if(base_pointer != (u32)-1)
 				stack_pointer[spill_slot] += stack_pointer[base_pointer];
 		}
 	}