diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 495d82786e..4c8967af39 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -945,7 +945,7 @@ pub fn (mut g Gen) write_alias_typesymbol_declaration(sym ast.TypeSymbol) {
 
 pub fn (mut g Gen) write_interface_typedef(sym ast.TypeSymbol) {
 	struct_name := c_name(sym.cname)
-	g.type_definitions.writeln('typedef struct $struct_name $struct_name;')
+	g.typedefs.writeln('typedef struct $struct_name $struct_name;')
 }
 
 pub fn (mut g Gen) write_interface_typesymbol_declaration(sym ast.TypeSymbol) {
diff --git a/vlib/v/tests/fn_test.v b/vlib/v/tests/fn_test.v
index b85fb9aa4d..6555127c4d 100644
--- a/vlib/v/tests/fn_test.v
+++ b/vlib/v/tests/fn_test.v
@@ -47,6 +47,10 @@ type F7 = fn (time.Time, int)
 type MyTime = time.Time
 type F8 = fn (MyTime)
 
+interface MyInterface {}
+
+type F9 = fn (MyInterface)
+
 fn C.atoi(&byte) int
 fn C.freec(ptr voidptr)