diff --git a/src/ast.zig b/src/ast.zig
index f1945590..8a4f287a 100644
--- a/src/ast.zig
+++ b/src/ast.zig
@@ -847,6 +847,11 @@ pub const ForeignClassDecl = struct {
     /// True when the sx-side alias NAME was a backtick raw identifier — exempt
     /// from the reserved-type-name decl check (issue 0089).
     is_raw: bool = false,
+    /// Defining module path (stamped by `resolveImports`), so the IMP trampolines
+    /// emitted for an sx-defined class resolve their method-signature types in the
+    /// module that declares the class — not the (cross-module) lowering site that
+    /// happens to trigger emission (E4). Null for a synthesized/sourceless decl.
+    source_file: ?[]const u8 = null,
 };
 
 pub const JniEnvBlock = struct {
diff --git a/src/imports.zig b/src/imports.zig
index dc5c177f..af535cdb 100644
--- a/src/imports.zig
+++ b/src/imports.zig
@@ -666,6 +666,13 @@ fn stampFnBodySource(decl: *Node, file_path: []const u8) void {
         // defining path so the instantiation resolves method-signature types in
         // this module (E4).
         .protocol_decl => decl.data.protocol_decl.source_file = file_path,
+        // An sx-defined `#objc_class` / `#jni_class`: its IMP trampolines are
+        // emitted at lowering time (possibly from another module's context), so
+        // record the defining path AND stamp each method body (E4).
+        .foreign_class_decl => {
+            decl.data.foreign_class_decl.source_file = file_path;
+            stampForeignClassMethodSources(decl.data.foreign_class_decl, file_path);
+        },
         .const_decl => |cd| switch (cd.value.data) {
             .fn_decl => |fd| fd.body.source_file = file_path,
             // `List :: struct { … append :: (…) { … } }` — the methods of a
@@ -674,6 +681,10 @@ fn stampFnBodySource(decl: *Node, file_path: []const u8) void {
             // bodies need the defining path stamped just like a top-level fn.
             .struct_decl => |sd| stampStructMethodSources(sd, file_path),
             .protocol_decl => cd.value.data.protocol_decl.source_file = file_path,
+            .foreign_class_decl => {
+                cd.value.data.foreign_class_decl.source_file = file_path;
+                stampForeignClassMethodSources(cd.value.data.foreign_class_decl, file_path);
+            },
             else => {},
         },
         else => {},
@@ -694,6 +705,16 @@ fn stampStructMethodSources(sd: ast.StructDecl, file_path: []const u8) void {
     }
 }
 
+/// Stamp the defining module path onto every bodied method of an sx-defined
+/// foreign class, so the method's sx body lowers in the class's own module.
+fn stampForeignClassMethodSources(fcd: ast.ForeignClassDecl, file_path: []const u8) void {
+    for (fcd.members) |m| {
+        if (m == .method) {
+            if (m.method.body) |b| b.source_file = file_path;
+        }
+    }
+}
+
 /// `reportDuplicateName` keyed off a node whose `declName()` carries the name
 /// (the regular authored-decl sites; an `import_decl` has no `declName`, so a
 /// namespace alias must use `reportDuplicateName` with the alias directly).
diff --git a/src/ir/lower.zig b/src/ir/lower.zig
index 545c24ff..b4c9890a 100644
--- a/src/ir/lower.zig
+++ b/src/ir/lower.zig
@@ -2231,9 +2231,6 @@ pub const Lowering = struct {
     fn resolveNominalLeaf(self: *Lowering, name: []const u8, raw: bool, span: ?ast.Span) TypeId {
         const from = self.current_source_file orelse
             return self.typeResolver().resolveName(name, raw);
-        if (std.mem.eql(u8, name, "BOOL")) {
-            std.debug.print("[BOOLLEAF] from={s} -> {s}\n", .{ from, @tagName(self.selectNominalLeaf(name, from, raw)) });
-        }
         return switch (self.selectNominalLeaf(name, from, raw)) {
             .resolved => |t| t,
             // A forward alias (`.pending`) or a forward / not-yet-interned named
@@ -18042,6 +18039,12 @@ pub const Lowering = struct {
     fn emitObjcDefinedClassImps(self: *Lowering) void {
         for (self.module.objc_defined_class_cache.items) |entry| {
             const fcd = entry.decl;
+            // Pin to the class's defining module (E4) so the IMP trampolines'
+            // method-signature types (`-> BOOL`, param types) resolve where they
+            // are visible, not at whatever lowering site triggered emission.
+            const saved_src = self.current_source_file;
+            defer self.setCurrentSourceFile(saved_src);
+            if (fcd.source_file) |src| self.setCurrentSourceFile(src);
             // Synthesize +alloc (M1.2 A.5) and -dealloc (M1.2 A.6). emit_llvm
             // registers +alloc on the metaclass and -dealloc on the class
             // itself after objc_registerClassPair.