diff --git a/makefile b/makefile
index c514751..c4b8bff 100644
--- a/makefile
+++ b/makefile
@@ -16,6 +16,7 @@ test:nasal
 	@ ./nasal -op -e -d test/calc.nas
 	@ ./nasal -op -e test/choice.nas
 	@ ./nasal -op -e test/class.nas
+	@ ./nasal -op -e test/diff.nas
 	-@ ./nasal -op -d test/exception.nas
 	@ ./nasal -op -t -d test/fib.nas
 	@ ./nasal -op -e test/filesystem.nas
diff --git a/nasal_builtin.h b/nasal_builtin.h
index 4830bab..22d5626 100644
--- a/nasal_builtin.h
+++ b/nasal_builtin.h
@@ -424,7 +424,7 @@ nasal_ref builtin_str(nasal_ref* local,nasal_gc& gc)
 nasal_ref builtin_size(nasal_ref* local,nasal_gc& gc)
 {
     nasal_ref val=local[1];
-    double num;
+    double num=0;
     switch(val.type)
     {
         case vm_num:  num=val.num();         break;
diff --git a/test/calc.nas b/test/calc.nas
index 77b6f27..35f1a0d 100644
--- a/test/calc.nas
+++ b/test/calc.nas
@@ -38,6 +38,7 @@ var testfile=[
     "test/calc.nas         ",
     "test/choice.nas       ",
     "test/class.nas        ",
+    "test/diff.nas         ",
     "test/exception.nas    ",
     "test/fib.nas          ",
     "test/filesystem.nas   ",
diff --git a/test/scalar.nas b/test/scalar.nas
index 1c16f5b..49f46a8 100644
--- a/test/scalar.nas
+++ b/test/scalar.nas
@@ -191,4 +191,10 @@ var a={
     }
 };
 println(isa(a.new(),a)); # 1
-println(isa(a.new2(),a));# 0
\ No newline at end of file
+println(isa(a.new2(),a));# 0
+
+var a=[10,-10,0,1,2,3,nil,"string","hello",[],[0,1,2,3],{},{a:0,b:1,c:2},func{}];
+println("type\tsize\tnum\tsrc");
+foreach(var i;a){
+    println(typeof(i),'\t',size(i),'\t',num(i),'\t',i);
+}
\ No newline at end of file