diff --git a/lib.nas b/lib.nas
index 68c97ec..5daf404 100644
--- a/lib.nas
+++ b/lib.nas
@@ -263,23 +263,6 @@ var math=
     isnan: func(x)  {return __builtin_isnan(x);  }
 };
 
-var D2R=math.pi/180;
-var FPS2KT=0.5925;
-var FT2M=0.3048;
-var GAL2L=3.7854;
-var IN2M=0.0254;
-var KG2LB=2.2046;
-var KT2FPS=1.6878;
-var KT2MPS=0.5144;
-var L2GAL=0.2642;
-var LB2KG=0.4536;
-var M2FT=3.2808;
-var M2IN=39.3701;
-var M2NM=0.00054;
-var MPS2KT=1.9438;
-var NM2M=1852;
-var R2D=180/math.pi;
-
 var unix=
 {
     pipe:     func(){die("not supported yet");},
@@ -327,4 +310,22 @@ var runtime=
     # do garbage collection manually.
     # carefully use it because using it frequently may make program running slower.
     gc: func(){return __builtin_gc;}
-};
\ No newline at end of file
+};
+
+# important global constants
+var D2R=math.pi/180;
+var FPS2KT=0.5925;
+var FT2M=0.3048;
+var GAL2L=3.7854;
+var IN2M=0.0254;
+var KG2LB=2.2046;
+var KT2FPS=1.6878;
+var KT2MPS=0.5144;
+var L2GAL=0.2642;
+var LB2KG=0.4536;
+var M2FT=3.2808;
+var M2IN=39.3701;
+var M2NM=0.00054;
+var MPS2KT=1.9438;
+var NM2M=1852;
+var R2D=180/math.pi;
\ No newline at end of file
diff --git a/makefile b/makefile
index 648db94..d65347d 100644
--- a/makefile
+++ b/makefile
@@ -20,7 +20,7 @@ test:nasal
 	./nasal -op -e -d test/lexer.nas
 	./nasal -op -e -d test/life.nas
 	./nasal -op -t test/loop.nas
-	./nasal -op -c test/mandel.nas
+	./nasal -op -t -d test/mandel.nas
 	./nasal -op -t -d test/mandelbrot.nas
 	./nasal -op -c test/module_test.nas
 	./nasal -op -e test/nasal_test.nas
diff --git a/nasal_gc.h b/nasal_gc.h
index bc141fb..552f93a 100644
--- a/nasal_gc.h
+++ b/nasal_gc.h
@@ -322,7 +322,7 @@ struct nasal_gc
     std::vector<nasal_val*> memory;                  // gc memory
     std::queue<nasal_val*>  free_list[vm_type_size]; // gc free list
     std::vector<nasal_ref>  local;
-    size_t                  size[vm_type_size];
+    uint64_t                size[vm_type_size];
     uint64_t                count[vm_type_size];
     void                    mark();
     void                    sweep();
@@ -390,10 +390,7 @@ void nasal_gc::sweep()
 void nasal_gc::init(const std::vector<std::string>& s)
 {
     for(uint8_t i=0;i<vm_type_size;++i)
-    {
-        size[i]=increment[i];
-        count[i]=0;
-    }
+        size[i]=count[i]=0;
     for(uint8_t i=vm_str;i<vm_type_size;++i)
         for(uint32_t j=0;j<increment[i];++j)
         {
@@ -436,7 +433,7 @@ void nasal_gc::info()
         std::cout<<name[i]<<" | "<<count[i]<<"\n";
     std::cout<<"\nmemory allocator info(max size):\n";
     for(uint8_t i=vm_str;i<vm_type_size;++i)
-        std::cout<<name[i]<<" | "<<size[i]<<"(+"<<size[i]/increment[i]-1<<")\n";
+        std::cout<<name[i]<<" | "<<(size[i]+1)*increment[i]<<"(+"<<size[i]<<")\n";
 }
 nasal_ref nasal_gc::alloc(uint8_t type)
 {
@@ -448,7 +445,7 @@ nasal_ref nasal_gc::alloc(uint8_t type)
     }
     if(free_list[type].empty())
     {
-        size[type]+=increment[type];
+        ++size[type];
         for(uint32_t i=0;i<increment[type];++i)
         {
             nasal_val* tmp=new nasal_val(type);
@@ -469,7 +466,7 @@ nasal_ref nasal_gc::builtin_alloc(uint8_t type)
     // so use builtin_alloc in builtin functions if this function uses alloc more then one time
     if(free_list[type].empty())
     {
-        size[type]+=increment[type];
+        ++size[type];
         for(uint32_t i=0;i<increment[type];++i)
         {
             nasal_val* tmp=new nasal_val(type);
diff --git a/stl/lib.nas b/stl/lib.nas
index 68c97ec..5daf404 100644
--- a/stl/lib.nas
+++ b/stl/lib.nas
@@ -263,23 +263,6 @@ var math=
     isnan: func(x)  {return __builtin_isnan(x);  }
 };
 
-var D2R=math.pi/180;
-var FPS2KT=0.5925;
-var FT2M=0.3048;
-var GAL2L=3.7854;
-var IN2M=0.0254;
-var KG2LB=2.2046;
-var KT2FPS=1.6878;
-var KT2MPS=0.5144;
-var L2GAL=0.2642;
-var LB2KG=0.4536;
-var M2FT=3.2808;
-var M2IN=39.3701;
-var M2NM=0.00054;
-var MPS2KT=1.9438;
-var NM2M=1852;
-var R2D=180/math.pi;
-
 var unix=
 {
     pipe:     func(){die("not supported yet");},
@@ -327,4 +310,22 @@ var runtime=
     # do garbage collection manually.
     # carefully use it because using it frequently may make program running slower.
     gc: func(){return __builtin_gc;}
-};
\ No newline at end of file
+};
+
+# important global constants
+var D2R=math.pi/180;
+var FPS2KT=0.5925;
+var FT2M=0.3048;
+var GAL2L=3.7854;
+var IN2M=0.0254;
+var KG2LB=2.2046;
+var KT2FPS=1.6878;
+var KT2MPS=0.5144;
+var L2GAL=0.2642;
+var LB2KG=0.4536;
+var M2FT=3.2808;
+var M2IN=39.3701;
+var M2NM=0.00054;
+var MPS2KT=1.9438;
+var NM2M=1852;
+var R2D=180/math.pi;
\ No newline at end of file