diff --git a/compiler/module/src/symbol.rs b/compiler/module/src/symbol.rs
index 65b8d366cf..ceb6748d80 100644
--- a/compiler/module/src/symbol.rs
+++ b/compiler/module/src/symbol.rs
@@ -877,6 +877,9 @@ define_builtins! {
 
         // used in wasm dev backend to mark temporary values in the VM stack
         24 WASM_TMP: "#wasm_tmp"
+
+        // the _ used in mono when a specialized symbol is deleted
+        25 DELETED_SPECIALIZATION: "#deleted_specialization"
     }
     1 NUM: "Num" => {
         0 NUM_NUM: "Num" imported // the Num.Num type alias
diff --git a/compiler/mono/src/ir.rs b/compiler/mono/src/ir.rs
index 268ba249f7..3f791837a9 100644
--- a/compiler/mono/src/ir.rs
+++ b/compiler/mono/src/ir.rs
@@ -544,8 +544,7 @@ impl<'a> Specialized<'a> {
             .zip(self.proc_layouts.into_iter())
             .zip(self.procedures.into_iter())
             .filter_map(|((s, l), in_progress)| {
-                // we use UNDERSCORE for removed symbols
-                if let Symbol::UNDERSCORE = s {
+                if let Symbol::REMOVED_SPECIALIZATION = s {
                     None
                 } else {
                     match in_progress {
@@ -596,8 +595,7 @@ impl<'a> Specialized<'a> {
         }
 
         if let Some(index) = index {
-            // we use UNDERSCORE for removed symbols
-            self.symbols[index] = Symbol::UNDERSCORE;
+            self.symbols[index] = Symbol::REMOVED_SPECIALIZATION;
 
             true
         } else {