diff --git a/src/mir/phi_core/loop_phi.rs b/src/mir/phi_core/loop_phi.rs
index 49087df7..47eca99a 100644
--- a/src/mir/phi_core/loop_phi.rs
+++ b/src/mir/phi_core/loop_phi.rs
@@ -170,11 +170,10 @@ pub fn prepare_loop_variables_with<O: LoopPhiOps>(
 
     let mut incomplete_phis: Vec<IncompletePhi> = Vec::new();
     for (var_name, &value_before) in current_vars.iter() {
-        // Skip pinned variables (internal compiler temporaries)
-        if var_name.starts_with("__pin$") {
-            // Pinned variables are materialized via entry-phi in loop body, skip here
-            continue;
-        }
+        // Phase 25.1b fix: Include pinned variables in loop header PHIs
+        // Previously pinned variables were skipped, causing "use of undefined value"
+        // errors when receivers were used after loops. Pinned variables need PHIs
+        // at both header and exit points to properly merge values across control flow.
 
         // Materialize the incoming value at preheader to satisfy UseBeforeDef constraints
         // even when `value_before` was defined in a different block (e.g., previous loop header).