3 files changed, 12 insertions, 6 deletions
diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 51909c6ff..3feebd121 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -1998,6 +1998,7 @@ struct PrintExpressionContents
   }
   void visitTupleExtract(TupleExtract* curr) {
     printMedium(o, "tuple.extract ");
+    o << curr->tuple->type.size() << " ";
     o << curr->index;
   }
   void visitRefI31(RefI31* curr) { printMedium(o, "ref.i31"); }
diff --git a/src/passes/TupleOptimization.cpp b/src/passes/TupleOptimization.cpp
index 16a2bad58..25da1c5ec 100644
--- a/src/passes/TupleOptimization.cpp
+++ b/src/passes/TupleOptimization.cpp
@@ -22,7 +22,7 @@
 //  (local.set $tuple
 //    (tuple.make 3 (A) (B) (C)))
 //  (use
-//    (tuple.extract 0
+//    (tuple.extract 3 0
 //      (local.get $tuple)))
 //
 // If there are no other uses, then we just need one of the three lanes. By
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 521060749..94b434dfb 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -2872,11 +2872,16 @@ Expression* SExpressionWasmBuilder::makeTupleMake(Element& s) {
 
 Expression* SExpressionWasmBuilder::makeTupleExtract(Element& s) {
   auto ret = allocator.alloc<TupleExtract>();
-  ret->index = parseIndex(*s[1]);
-  ret->tuple = parseExpression(s[2]);
-  if (ret->tuple->type != Type::unreachable &&
-      ret->index >= ret->tuple->type.size()) {
-    throw SParseException("Bad index on tuple.extract", s, *s[1]);
+  size_t arity = std::stoll(s[1]->toString());
+  ret->index = parseIndex(*s[2]);
+  ret->tuple = parseExpression(s[3]);
+  if (ret->tuple->type != Type::unreachable) {
+    if (arity != ret->tuple->type.size()) {
+      throw SParseException("Unexpected tuple.extract arity", s, *s[1]);
+    }
+    if (ret->index >= ret->tuple->type.size()) {
+      throw SParseException("Bad index on tuple.extract", s, *s[2]);
+    }
   }
   ret->finalize();
   return ret;