diff --git a/src/offset_of.rs b/src/offset_of.rs
index 439c15d..aa8c222 100644
--- a/src/offset_of.rs
+++ b/src/offset_of.rs
@@ -42,6 +42,18 @@ macro_rules! let_base_ptr {
     }
 }
 
+/// Deref-coercion protection macro.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! field_check {
+    ($type:tt, $field:tt) => {
+        // Make sure the field actually exists. This line ensures that a
+        // compile-time error is generated if $field is accessed through a
+        // Deref impl.
+        let $type { $field: _, .. };
+    }
+}
+
 /// Calculates the offset of the specified field from the start of the struct.
 /// This macro supports arbitrary amount of subscripts and recursive member-accesses.
 ///
@@ -67,10 +79,7 @@ macro_rules! let_base_ptr {
 #[macro_export]
 macro_rules! offset_of {
     ($parent:tt, $field:tt) => {{
-        // Make sure the field actually exists. This line ensures that a
-        // compile-time error is generated if $field is accessed through a
-        // Deref impl.
-        let $parent { $field: _, .. };
+        field_check!($parent, $field);
 
         // Get a base pointer.
         $crate::let_base_ptr!(base_ptr, $parent);
diff --git a/src/span_of.rs b/src/span_of.rs
index 7741b4b..0111389 100644
--- a/src/span_of.rs
+++ b/src/span_of.rs
@@ -89,46 +89,46 @@ macro_rules! span_of {
     };
     // Lots of UB due to taking references to uninitialized fields! But that can currently
     // not be avoided.
-    (@helper $root:ident, [] ..= $($field:tt)+) => {
+    (@helper $root:ident, $parent:tt, [] ..= $($field:tt)*) => {{
         ($root as usize,
          &(*$root).$($field)* as *const _ as usize + $crate::mem::size_of_val(&(*$root).$($field)*))
-    };
-    (@helper $root:ident, [] .. $($field:tt)+) => {
+    }};
+    (@helper $root:ident, $parent:tt, [] .. $($field:tt)+) => {{
         ($root as usize, &(*$root).$($field)* as *const _ as usize)
-    };
-    (@helper $root:ident, $(# $begin:tt)+ [] ..= $($end:tt)+) => {
+    }};
+    (@helper $root:ident, $parent:tt, $(# $begin:tt)+ [] ..= $($end:tt)+) => {{
         (&(*$root).$($begin)* as *const _ as usize,
          &(*$root).$($end)* as *const _ as usize + $crate::mem::size_of_val(&(*$root).$($end)*))
-    };
-    (@helper $root:ident, $(# $begin:tt)+ [] .. $($end:tt)+) => {
+    }};
+    (@helper $root:ident, $parent:tt, $(# $begin:tt)+ [] .. $($end:tt)+) => {{
         (&(*$root).$($begin)* as *const _ as usize,
          &(*$root).$($end)* as *const _ as usize)
-    };
-    (@helper $root:ident, $(# $begin:tt)+ [] ..) => {
+    }};
+    (@helper $root:ident, $parent:tt, $(# $begin:tt)+ [] ..) => {{
         (&(*$root).$($begin)* as *const _ as usize,
          $root as usize + $crate::mem::size_of_val(&*$root))
-    };
-    (@helper $root:ident, $(# $begin:tt)+ [] ..=) => {
+    }};
+    (@helper $root:ident, $parent:tt, $(# $begin:tt)+ [] ..=) => {{
         compile_error!(
             "Found inclusive range to the end of a struct. Did you mean '..' instead of '..='?")
-    };
-    (@helper $root:ident, $(# $begin:tt)+ []) => {
+    }};
+    (@helper $root:ident, $parent:tt, $(# $begin:tt)+ []) => {{
         (&(*$root).$($begin)* as *const _ as usize,
          &(*$root).$($begin)* as *const _ as usize + $crate::mem::size_of_val(&(*$root).$($begin)*))
-    };
-    (@helper $root:ident, $(# $begin:tt)+ [] $tt:tt $($rest:tt)*) => {
-        span_of!(@helper $root, $(#$begin)* #$tt [] $($rest)*)
-    };
-    (@helper $root:ident, [] $tt:tt $($rest:tt)*) => {
-        span_of!(@helper $root, #$tt [] $($rest)*)
-    };
+    }};
+    (@helper $root:ident, $parent:tt, $(# $begin:tt)+ [] $tt:tt $($rest:tt)*) => {{
+        span_of!(@helper $root, $parent, $(#$begin)* #$tt [] $($rest)*)
+    }};
+    (@helper $root:ident, $parent:tt, [] $tt:tt $($rest:tt)*) => {{
+        span_of!(@helper $root, $parent, #$tt [] $($rest)*)
+    }};
 
     ($sty:tt, $($exp:tt)+) => ({
         unsafe {
             // Get a base pointer.
             $crate::let_base_ptr!(root, $sty);
             let base = root as usize;
-            let (begin, end) = span_of!(@helper root, [] $($exp)*);
+            let (begin, end) = span_of!(@helper root, $sty, [] $($exp)*);
             begin-base..end-base
         }
     });