diff --git a/selfhost/cmd/w6c/main.combined.ww b/selfhost/cmd/w6c/main.combined.ww
index bb00d4a9..f01a0f77 100644
--- a/selfhost/cmd/w6c/main.combined.ww
+++ b/selfhost/cmd/w6c/main.combined.ww
@@ -7607,7 +7607,16 @@ fn resolvealias(c: *checker, n: *node) *node = {
 			leaf.len = nm.len - dotidx - 1;
 			s = scopelookupinmodule(c.cur, head, leaf);
 		} else {
-			s = scopelookup(c.cur, nm);
+			// #53: same-module preference. Mirrors cstage
+			// cmd/wcc/check.c:66 scope_lookup_prefer. Without this,
+			// two modules each declaring `type invalid = ...` collide
+			// on the head-first bucket walk: e.g. utf8.invalid `!void`
+			// vs strconv.invalid `!i32` resolves to whichever
+			// registered first, driving localloadop MOVSXD/MOVQ
+			// divergence at 994/995. Other bare-leaf callers in this
+			// file (L1597 exprtype N_IDENT, L1795/L2720 N_DOT-callee
+			// leaf, L600 varianterr, L647 scruttype) tracked as #55.
+			s = scopelookupprefer(c.cur, c.curmod, nm);
 			// #61 A.5: bare TNAME that collides with an imported
 			// module bareword. Two shapes hit this:
 			//   - `let l: lex;` where `lex` struct lives in
diff --git a/selfhost/cmd/wcc/check.ww b/selfhost/cmd/wcc/check.ww
index 9cb23d6f..747d24f7 100644
--- a/selfhost/cmd/wcc/check.ww
+++ b/selfhost/cmd/wcc/check.ww
@@ -537,7 +537,16 @@ fn resolvealias(c: *checker, n: *node) *node = {
 			leaf.len = nm.len - dotidx - 1;
 			s = scopelookupinmodule(c.cur, head, leaf);
 		} else {
-			s = scopelookup(c.cur, nm);
+			// #53: same-module preference. Mirrors cstage
+			// cmd/wcc/check.c:66 scope_lookup_prefer. Without this,
+			// two modules each declaring `type invalid = ...` collide
+			// on the head-first bucket walk: e.g. utf8.invalid `!void`
+			// vs strconv.invalid `!i32` resolves to whichever
+			// registered first, driving localloadop MOVSXD/MOVQ
+			// divergence at 994/995. Other bare-leaf callers in this
+			// file (L1597 exprtype N_IDENT, L1795/L2720 N_DOT-callee
+			// leaf, L600 varianterr, L647 scruttype) tracked as #55.
+			s = scopelookupprefer(c.cur, c.curmod, nm);
 			// #61 A.5: bare TNAME that collides with an imported
 			// module bareword. Two shapes hit this:
 			//   - `let l: lex;` where `lex` struct lives in
diff --git a/selfhost/cmd/wwdump/main.combined.ww b/selfhost/cmd/wwdump/main.combined.ww
index 87dcf619..35091826 100644
--- a/selfhost/cmd/wwdump/main.combined.ww
+++ b/selfhost/cmd/wwdump/main.combined.ww
@@ -7607,7 +7607,16 @@ fn resolvealias(c: *checker, n: *node) *node = {
 			leaf.len = nm.len - dotidx - 1;
 			s = scopelookupinmodule(c.cur, head, leaf);
 		} else {
-			s = scopelookup(c.cur, nm);
+			// #53: same-module preference. Mirrors cstage
+			// cmd/wcc/check.c:66 scope_lookup_prefer. Without this,
+			// two modules each declaring `type invalid = ...` collide
+			// on the head-first bucket walk: e.g. utf8.invalid `!void`
+			// vs strconv.invalid `!i32` resolves to whichever
+			// registered first, driving localloadop MOVSXD/MOVQ
+			// divergence at 994/995. Other bare-leaf callers in this
+			// file (L1597 exprtype N_IDENT, L1795/L2720 N_DOT-callee
+			// leaf, L600 varianterr, L647 scruttype) tracked as #55.
+			s = scopelookupprefer(c.cur, c.curmod, nm);
 			// #61 A.5: bare TNAME that collides with an imported
 			// module bareword. Two shapes hit this:
 			//   - `let l: lex;` where `lex` struct lives in