diff --git a/vlib/v/gen/c/assign.v b/vlib/v/gen/c/assign.v
index 7bfc255c711635..874670b9c2caf1 100644
--- a/vlib/v/gen/c/assign.v
+++ b/vlib/v/gen/c/assign.v
@@ -729,7 +729,13 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 						cloned = true
 					}
 				} else if right_sym.kind == .interface {
-					g.get_free_method(var_type)
+					if g.table.type_to_str(var_type) != 'IError' {
+						if var_type.has_flag(.shared_f) {
+							g.get_free_method(var_type.clear_flag(.shared_f).set_nr_muls(0))
+						} else {
+							g.get_free_method(var_type)
+						}
+					}
 				}
 			}
 			if !cloned {
diff --git a/vlib/v/gen/c/auto_free_methods.v b/vlib/v/gen/c/auto_free_methods.v
index d1196dcf97e491..223d473112d3a6 100644
--- a/vlib/v/gen/c/auto_free_methods.v
+++ b/vlib/v/gen/c/auto_free_methods.v
@@ -6,7 +6,9 @@ import v.ast
 import strings
 
 fn (mut g Gen) get_free_method(typ ast.Type) string {
-	g.autofree_methods[typ] = true
+	if typ in g.autofree_methods {
+		return g.autofree_methods[typ]
+	}
 	mut sym := g.table.sym(g.unwrap_generic(typ))
 	if mut sym.info is ast.Alias {
 		if sym.info.is_import {
@@ -16,8 +18,10 @@ fn (mut g Gen) get_free_method(typ ast.Type) string {
 	styp := g.typ(typ).replace('*', '')
 	fn_name := styp_to_free_fn_name(styp)
 	if sym.has_method_with_generic_parent('free') {
+		g.autofree_methods[typ] = fn_name
 		return fn_name
 	}
+	g.autofree_methods[typ] = fn_name
 	return fn_name
 }
 
@@ -78,12 +82,13 @@ fn (mut g Gen) gen_free_for_interface(sym ast.TypeSymbol, info ast.Interface, st
 	}
 	fn_builder.writeln('${g.static_modifier} void ${fn_name}(${styp}* it) {')
 	for t in info.types {
-		sub_sym := g.table.sym(ast.mktyp(t))
+		typ_ := g.unwrap_generic(t)
+		sub_sym := g.table.sym(typ_)
 		if sub_sym.kind !in [.string, .array, .map, .struct] {
 			continue
 		}
-		fn_name_typ := g.get_free_method(t)
-		fn_builder.writeln('\tif (it->_typ == _${sym.cname}_${sub_sym.cname}_index) { ${fn_name_typ}(it); return; }')
+		fn_name_typ := g.get_free_method(typ_)
+		fn_builder.writeln('\tif (it->_typ == _${sym.cname}_${sub_sym.cname}_index) { ${fn_name_typ}(it->_${sub_sym.cname}); return; }')
 	}
 	fn_builder.writeln('}')
 }
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 6f24e11518de4b..a956b057b704f1 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -245,7 +245,7 @@ mut:
 	cur_fn                 &ast.FnDecl = unsafe { nil } // same here
 	cur_lock               ast.LockExpr
 	cur_struct_init_typ    ast.Type
-	autofree_methods       map[int]bool
+	autofree_methods       map[int]string
 	generated_free_methods map[int]bool
 	autofree_scope_stmts   []string
 	use_segfault_handler   bool = true
diff --git a/vlib/v/gen/c/testdata/interface_auto_free.c.must_have b/vlib/v/gen/c/testdata/interface_auto_free.c.must_have
index 01ded274dcf830..41d8ea445035d7 100644
--- a/vlib/v/gen/c/testdata/interface_auto_free.c.must_have
+++ b/vlib/v/gen/c/testdata/interface_auto_free.c.must_have
@@ -1,7 +1,7 @@
- void main__IFoo_free(main__IFoo* it) {
-	if (it->_typ == _main__IFoo_main__Foo_index) { main__Foo_free(it); return; }
-	if (it->_typ == _main__IFoo_array_index) { array_free(it); return; }
-	if (it->_typ == _main__IFoo_map_index) { map_free(it); return; }
-	if (it->_typ == _main__IFoo_VAssertMetaInfo_index) { VAssertMetaInfo_free(it); return; }
-	if (it->_typ == _main__IFoo_MessageError_index) { MessageError_free(it); return; }
+void main__IFoo_free(main__IFoo* it) {
+	if (it->_typ == _main__IFoo_main__Foo_index) { main__Foo_free(it->_main__Foo); return; }
+	if (it->_typ == _main__IFoo_array_index) { array_free(it->_array); return; }
+	if (it->_typ == _main__IFoo_map_index) { map_free(it->_map); return; }
+	if (it->_typ == _main__IFoo_VAssertMetaInfo_index) { VAssertMetaInfo_free(it->_VAssertMetaInfo); return; }
+	if (it->_typ == _main__IFoo_MessageError_index) { MessageError_free(it->_MessageError); return; }
 }
\ No newline at end of file