diff --git a/rust/candid/src/de.rs b/rust/candid/src/de.rs
index 503b27a8..e26e093c 100644
--- a/rust/candid/src/de.rs
+++ b/rust/candid/src/de.rs
@@ -725,7 +725,6 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
     where
         V: Visitor<'de>,
     {
-        self.dec_value_cost(1)?;
         visitor.visit_newtype_struct(self)
     }
     fn deserialize_option<V>(self, visitor: V) -> Result<V::Value>
@@ -851,6 +850,7 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
                                 let expect = (ek.clone(), ev.clone());
                                 let wire = (wk.clone(), wv.clone());
                                 let len = Len::read(&mut self.input)?.0;
+                                self.dec_value_cost(len)?;
                                 visitor.visit_map(Compound::new(
                                     self,
                                     Style::Map { len, expect, wire },
@@ -1024,7 +1024,9 @@ impl<'de, 'a> de::SeqAccess<'de> for Compound<'a, 'de> {
                 if expect.is_empty() && wire.is_empty() {
                     return Ok(None);
                 }
-                self.de.dec_value_cost(1)?;
+                if !wire.is_empty() {
+                    self.de.dec_value_cost(1)?;
+                }
                 self.de.expect_type = expect
                     .pop_front()
                     .map(|f| f.ty)
@@ -1054,15 +1056,16 @@ impl<'de, 'a> de::MapAccess<'de> for Compound<'a, 'de> {
                 match (expect.front(), wire.front()) {
                     (Some(e), Some(w)) => {
                         use std::cmp::Ordering;
-                        self.de.dec_value_cost(1)?;
                         match e.id.get_id().cmp(&w.id.get_id()) {
                             Ordering::Equal => {
+                                self.de.dec_value_cost(1)?;
                                 self.de.set_field_name(e.id.clone());
                                 self.de.expect_type = expect.pop_front().unwrap().ty;
                                 self.de.wire_type = wire.pop_front().unwrap().ty;
                             }
                             Ordering::Less => {
                                 // by subtyping rules, expect_type can only be opt, reserved or null.
+                                self.de.value_cost += 1; // correct the later decrement from serialize_option of producing None.
                                 let field = e.id.clone();
                                 self.de.set_field_name(field.clone());
                                 let expect = expect.pop_front().unwrap().ty;
@@ -1077,6 +1080,7 @@ impl<'de, 'a> de::MapAccess<'de> for Compound<'a, 'de> {
                                 self.de.wire_type = TypeInner::Reserved.into();
                             }
                             Ordering::Greater => {
+                                self.de.dec_value_cost(1)?;
                                 self.de.set_field_name(Label::Named("_".to_owned()).into());
                                 self.de.wire_type = wire.pop_front().unwrap().ty;
                                 self.de.expect_type = TypeInner::Reserved.into();
@@ -1090,6 +1094,7 @@ impl<'de, 'a> de::MapAccess<'de> for Compound<'a, 'de> {
                         self.de.expect_type = TypeInner::Reserved.into();
                     }
                     (Some(e), None) => {
+                        self.de.value_cost += 1; // correct the later decrement from serialize_option of producing None.
                         self.de.set_field_name(e.id.clone());
                         self.de.expect_type = expect.pop_front().unwrap().ty;
                         self.de.wire_type = TypeInner::Reserved.into();
diff --git a/rust/candid/tests/serde.rs b/rust/candid/tests/serde.rs
index 26642781..06de25fc 100644
--- a/rust/candid/tests/serde.rs
+++ b/rust/candid/tests/serde.rs
@@ -760,10 +760,16 @@ where
     {
         use candid::types::value::IDLValue;
         let mut deserializer = candid::de::IDLDeserialize::new(bytes).unwrap();
-        let decoded = deserializer.get_value::<IDLValue>().unwrap();
-        let cost = deserializer.value_cost();
+        let _ = deserializer.get_value::<T>().unwrap();
+        let cost1 = deserializer.value_cost();
         let _ = deserializer.done().unwrap();
-        assert_eq!(cost, decoded.cost());
+
+        let mut deserializer = candid::de::IDLDeserialize::new(bytes).unwrap();
+        let value = deserializer.get_value::<IDLValue>().unwrap();
+        let cost2 = deserializer.value_cost();
+        let _ = deserializer.done().unwrap();
+        assert_eq!(cost1, cost2);
+        assert_eq!(cost2, value.cost());
     }
 }
 
diff --git a/test/spacebomb.test.did b/test/spacebomb.test.did
index 5c2d415c..85db704d 100644
--- a/test/spacebomb.test.did
+++ b/test/spacebomb.test.did
@@ -18,20 +18,6 @@ assert blob "DIDL\04\6c\03\01\7f\02\01\03\02\6c\01\01\70\6c\00\6d\00\01\03\80\94
 assert blob "DIDL\02\6d\01\6d\7f\01\00\05\ff\ff\3f\ff\ff\3f\ff\ff\3f\ff\ff\3f\ff\ff\3f"    !: () "vec vec null (extra argument)";
 assert blob "DIDL\03\6c\01\d6\fc\a7\02\01\6d\02\6c\00\01\00\80\ad\e2\04"                   !: () "vec record {} (extra argument)";
 
-// Messages with exactly 2_000_000 zero-length elements should succeed
-assert blob "DIDL\01\6d\7f\01\00\80\89\7a"                           : () "vec null (exactly 2000000)";
-assert blob "DIDL\01\6d\70\01\00\80\89\7a"                           : () "vec reserved (exactly 2000000)";
-assert blob "DIDL\04\6c\03\01\7f\02\01\03\02\6c\01\01\70\6c\00\6d\00\01\03\80\89\7a" : () "zero-sized record (exactly 2000000)";
-assert blob "DIDL\02\6d\01\6d\7f\01\00\05\80\b5\18\80\b5\18\80\b5\18\80\b5\18\80\b5\18" : () "vec vec null (exactly 2000000)";
-assert blob "DIDL\03\6c\01\d6\fc\a7\02\01\6d\02\6c\00\01\00\80\89\7a"                   : () "vec record {} (exactly 2000000)";
-
-// Messages with exactly 2_000_001 zero-length elements should fail
-assert blob "DIDL\01\6d\7f\01\00\80\89\7b"                           !: () "vec null (exactly 2000001)";
-assert blob "DIDL\01\6d\70\01\00\80\89\7b"                           !: () "vec reserved (exactly 2000001)";
-assert blob "DIDL\04\6c\03\01\7f\02\01\03\02\6c\01\01\70\6c\00\6d\00\01\03\80\89\7b" !: () "zero-sized record (exactly 2000001)";
-assert blob "DIDL\02\6d\01\6d\7f\01\00\05\80\b5\18\80\b5\18\80\b5\18\80\b5\18\80\b5\19" !: () "vec vec null (exactly 2000001)";
-assert blob "DIDL\03\6c\01\d6\fc\a7\02\01\6d\02\6c\00\01\00\80\89\7b"                   !: () "vec record {} (exactly 2000001)";
-
 // Decoding to actual type
 assert blob "DIDL\01\6d\7f\01\00\80\94\eb\dc\03"                           !: (vec opt nat) "vec null (not ignored)";
 assert blob "DIDL\01\6d\70\01\00\80\94\eb\dc\03"                           !: (vec reserved) "vec reserved (not ignored)";