diff --git a/src/dynamic.rs b/src/dynamic.rs
index 93e6d533..887e73d1 100644
--- a/src/dynamic.rs
+++ b/src/dynamic.rs
@@ -1447,9 +1447,9 @@ impl Dynamic {
     /// Exported under the `decimal` feature only.
     #[cfg(feature = "decimal")]
     #[inline(always)]
-    pub fn as_decimal(self) -> Result<Decimal, &'static str> {
-        match self.0 {
-            Union::Decimal(n, _) => Ok(*n),
+    pub fn as_decimal(&self) -> Result<Decimal, &'static str> {
+        match &self.0 {
+            Union::Decimal(n, _) => Ok(**n),
             #[cfg(not(feature = "no_closure"))]
             Union::Shared(_, _) => self.read_lock().map(|v| *v).ok_or_else(|| self.type_name()),
             _ => Err(self.type_name()),
diff --git a/src/fn_builtin.rs b/src/fn_builtin.rs
index 28a7283c..b81cd500 100644
--- a/src/fn_builtin.rs
+++ b/src/fn_builtin.rs
@@ -946,27 +946,32 @@ pub fn get_builtin_op_assignment_fn(
             match op {
                 "+=" => {
                     return Some(|_, args| {
-                        Ok((*args[0].write_lock::<Decimal>().unwrap() += get_y(args)).into())
+                        let y = get_y(args);
+                        Ok((*args[0].write_lock::<Decimal>().unwrap() += y).into())
                     })
                 }
                 "-=" => {
                     return Some(|_, args| {
-                        Ok((*args[0].write_lock::<Decimal>().unwrap() -= get_y(args)).into())
+                        let y = get_y(args);
+                        Ok((*args[0].write_lock::<Decimal>().unwrap() -= y).into())
                     })
                 }
                 "*=" => {
                     return Some(|_, args| {
-                        Ok((*args[0].write_lock::<Decimal>().unwrap() *= get_y(args)).into())
+                        let y = get_y(args);
+                        Ok((*args[0].write_lock::<Decimal>().unwrap() *= y).into())
                     })
                 }
                 "/=" => {
                     return Some(|_, args| {
-                        Ok((*args[0].write_lock::<Decimal>().unwrap() /= get_y(args)).into())
+                        let y = get_y(args);
+                        Ok((*args[0].write_lock::<Decimal>().unwrap() /= y).into())
                     })
                 }
                 "%=" => {
                     return Some(|_, args| {
-                        Ok((*args[0].write_lock::<Decimal>().unwrap() %= get_y(args)).into())
+                        let y = get_y(args);
+                        Ok((*args[0].write_lock::<Decimal>().unwrap() %= y).into())
                     })
                 }
                 _ => return None,
diff --git a/src/lib.rs b/src/lib.rs
index 166b0c07..ae0dc0f9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -88,7 +88,7 @@ mod token;
 mod r#unsafe;
 mod utils;
 
-pub type RhaiResult = Result<Dynamic, Box<EvalAltResult>>;
+pub type RhaiResult = Result<Dynamic, stdlib::boxed::Box<EvalAltResult>>;
 
 /// The system integer type. It is defined as [`i64`].
 ///