diff --git a/vlib/v/gen/c/assign.v b/vlib/v/gen/c/assign.v
index b2df3b9daf5d7c..4d3fda156d47a3 100644
--- a/vlib/v/gen/c/assign.v
+++ b/vlib/v/gen/c/assign.v
@@ -1015,7 +1015,8 @@ fn (mut g Gen) gen_cross_var_assign(node &ast.AssignStmt) {
 					}
 				}
 				if left_sym.kind == .function {
-					g.write_fn_ptr_decl(left_sym.info as ast.FnType, '_var_${left.pos.pos}')
+					g.write_fn_ptr_decl(left_sym.info as ast.FnType, '_var_${left.pos.pos}',
+						true)
 					g.writeln(' = ${anon_ctx}${c_name(left.name)};')
 				} else if left_is_auto_deref_var {
 					styp := g.styp(left_typ).trim('*')
@@ -1043,7 +1044,8 @@ fn (mut g Gen) gen_cross_var_assign(node &ast.AssignStmt) {
 					if elem_typ.kind == .function {
 						left_typ := node.left_types[i]
 						left_sym := g.table.sym(left_typ)
-						g.write_fn_ptr_decl(left_sym.info as ast.FnType, '_var_${left.pos.pos}')
+						g.write_fn_ptr_decl(left_sym.info as ast.FnType, '_var_${left.pos.pos}',
+							true)
 						g.write(' = *(voidptr*)array_get(')
 					} else {
 						styp := g.styp(info.elem_type)
@@ -1068,7 +1070,8 @@ fn (mut g Gen) gen_cross_var_assign(node &ast.AssignStmt) {
 					if elem_typ.kind == .function {
 						left_typ := node.left_types[i]
 						left_sym := g.table.sym(left_typ)
-						g.write_fn_ptr_decl(left_sym.info as ast.FnType, '_var_${left.pos.pos}')
+						g.write_fn_ptr_decl(left_sym.info as ast.FnType, '_var_${left.pos.pos}',
+							true)
 						g.write(' = *(voidptr*)')
 					} else {
 						styp := g.styp(info.elem_type)
@@ -1095,7 +1098,8 @@ fn (mut g Gen) gen_cross_var_assign(node &ast.AssignStmt) {
 					if val_typ.kind == .function {
 						left_type := node.left_types[i]
 						left_sym := g.table.sym(left_type)
-						g.write_fn_ptr_decl(left_sym.info as ast.FnType, '_var_${left.pos.pos}')
+						g.write_fn_ptr_decl(left_sym.info as ast.FnType, '_var_${left.pos.pos}',
+							true)
 						g.write(' = *(voidptr*)map_get(')
 					} else {
 						g.write('${styp} _var_${left.pos.pos} = *(${styp}*)map_get(')
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 909660238b5297..65828c3b767d95 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -1654,7 +1654,7 @@ pub fn (mut g Gen) write_typedef_types() {
 						if elem_sym.info is ast.FnType {
 							pos := g.out.len
 							// pos2:=g.out_parallel[g.out_idx].len
-							g.write_fn_ptr_decl(&elem_sym.info, '')
+							g.write_fn_ptr_decl(&elem_sym.info, '', true)
 							fixed = g.out.cut_to(pos)
 							// g.out_parallel[g.out_idx].cut_to(pos2)
 							mut def_str := 'typedef ${fixed};'
@@ -2172,13 +2172,14 @@ fn (mut g Gen) expr_with_tmp_var(expr ast.Expr, expr_typ ast.Type, ret_typ ast.T
 	stmt_str := g.go_before_last_stmt().trim_space()
 	mut styp := g.base_type(ret_typ)
 	g.empty_line = true
+	final_expr_sym := g.table.final_sym(expr_typ)
 
-	if g.table.sym(expr_typ).kind == .none {
+	if final_expr_sym.kind == .none {
 		g.write('${g.styp(ret_typ)} ${tmp_var} = ')
 		g.gen_option_error(ret_typ, expr)
 		g.writeln(';')
 	} else if expr is ast.Ident && expr_typ == ast.error_type {
-		g.writeln('${g.styp(ret_typ)} ${tmp_var} = {.state=2, .err = ${expr.name}};')
+		g.writeln('${g.styp(ret_typ)} ${tmp_var} = {.state=2, .err=${expr.name}};')
 	} else {
 		mut simple_assign := false
 		if ret_typ.has_flag(.generic) {
@@ -2225,6 +2226,14 @@ fn (mut g Gen) expr_with_tmp_var(expr ast.Expr, expr_typ ast.Type, ret_typ ast.T
 					g.write('_option_none(&(${styp}[]) { ')
 				} else {
 					g.write('_option_ok(&(${styp}[]) { ')
+					if final_expr_sym.info is ast.FnType {
+						final_ret_sym := g.table.final_sym(ret_typ)
+						if final_ret_sym.info is ast.FnType {
+							g.write('(')
+							g.write_fn_ptr_decl(&final_ret_sym.info, '', false)
+							g.write(')')
+						}
+					}
 				}
 				if ret_typ.nr_muls() > expr_typ.nr_muls() {
 					g.write('&'.repeat(ret_typ.nr_muls() - expr_typ.nr_muls()))
@@ -3192,13 +3201,16 @@ fn cnewlines(s string) string {
 	return s.replace('\n', r'\n')
 }
 
-fn (mut g Gen) write_fn_ptr_decl(func &ast.FnType, ptr_name string) {
+fn (mut g Gen) write_fn_ptr_decl(func &ast.FnType, ptr_name string, with_argname bool) {
 	ret_styp := g.styp(func.func.return_type)
 	g.write('${ret_styp} (*${ptr_name}) (')
 	arg_len := func.func.params.len
 	for i, arg in func.func.params {
 		arg_styp := g.styp(arg.typ)
-		g.write('${arg_styp} ${arg.name}')
+		g.write(arg_styp)
+		if with_argname {
+			g.write(' ${arg.name}')
+		}
 		if i < arg_len - 1 {
 			g.write(', ')
 		}
@@ -6625,7 +6637,7 @@ fn (mut g Gen) write_types(symbols []&ast.TypeSymbol) {
 					if len > 0 {
 						if elem_sym.info is ast.FnType {
 							pos := g.out.len
-							g.write_fn_ptr_decl(&elem_sym.info, '')
+							g.write_fn_ptr_decl(&elem_sym.info, '', true)
 							fixed_elem_name = g.out.cut_to(pos)
 							mut def_str := 'typedef ${fixed_elem_name};'
 							def_str = def_str.replace_once('(*)', '(*${styp}[${len}])')
diff --git a/vlib/v/gen/c/dumpexpr.v b/vlib/v/gen/c/dumpexpr.v
index 246a07388280af..def2a38a160dd3 100644
--- a/vlib/v/gen/c/dumpexpr.v
+++ b/vlib/v/gen/c/dumpexpr.v
@@ -133,7 +133,7 @@ fn (mut g Gen) dump_expr_definitions() {
 			fninfo := dump_sym.info as ast.FnType
 			str_dumparg_type = 'DumpFNType_${name}'
 			tdef_pos := g.out.len
-			g.write_fn_ptr_decl(&fninfo, str_dumparg_type)
+			g.write_fn_ptr_decl(&fninfo, str_dumparg_type, true)
 			str_tdef := g.out.after(tdef_pos)
 			g.go_back(str_tdef.len)
 			dump_typedefs['typedef ${str_tdef};'] = true
diff --git a/vlib/v/gen/c/for.v b/vlib/v/gen/c/for.v
index 944a3a76c84faa..b93d58fa9d6fe2 100644
--- a/vlib/v/gen/c/for.v
+++ b/vlib/v/gen/c/for.v
@@ -260,7 +260,8 @@ fn (mut g Gen) for_in_stmt(node_ ast.ForInStmt) {
 		if node.val_var != '_' {
 			if val_sym.kind == .function {
 				g.write('\t')
-				g.write_fn_ptr_decl(val_sym.info as ast.FnType, c_name(node.val_var))
+				g.write_fn_ptr_decl(val_sym.info as ast.FnType, c_name(node.val_var),
+					true)
 				g.writeln(' = ((voidptr*)${cond_var}${op_field}data)[${i}];')
 			} else if val_sym.kind == .array_fixed && !node.val_is_mut {
 				right := '((${styp}*)${cond_var}${op_field}data)[${i}]'
@@ -322,7 +323,8 @@ fn (mut g Gen) for_in_stmt(node_ ast.ForInStmt) {
 			is_fixed_array := val_sym.kind == .array_fixed && !node.val_is_mut
 			if val_sym.kind == .function {
 				g.write('\t')
-				g.write_fn_ptr_decl(val_sym.info as ast.FnType, c_name(node.val_var))
+				g.write_fn_ptr_decl(val_sym.info as ast.FnType, c_name(node.val_var),
+					true)
 			} else if is_fixed_array {
 				styp := g.styp(node.val_type)
 				g.writeln('\t${styp} ${c_name(node.val_var)};')
@@ -388,7 +390,8 @@ fn (mut g Gen) for_in_stmt(node_ ast.ForInStmt) {
 		if node.val_var != '_' {
 			val_sym := g.table.sym(node.val_type)
 			if val_sym.kind == .function {
-				g.write_fn_ptr_decl(val_sym.info as ast.FnType, c_name(node.val_var))
+				g.write_fn_ptr_decl(val_sym.info as ast.FnType, c_name(node.val_var),
+					true)
 				g.write(' = (*(voidptr*)')
 				g.writeln('DenseArray_value(&${cond_var}${dot_or_ptr}key_values, ${idx}));')
 			} else if val_sym.kind == .array_fixed && !node.val_is_mut {
diff --git a/vlib/v/gen/c/index.v b/vlib/v/gen/c/index.v
index 8a1d59fac3782e..3472f1366f15a0 100644
--- a/vlib/v/gen/c/index.v
+++ b/vlib/v/gen/c/index.v
@@ -261,7 +261,7 @@ fn (mut g Gen) index_of_array(node ast.IndexExpr, sym ast.TypeSymbol) {
 			if is_fn_index_call {
 				if elem_sym.info is ast.FnType {
 					g.write('((')
-					g.write_fn_ptr_decl(&elem_sym.info, '')
+					g.write_fn_ptr_decl(&elem_sym.info, '', true)
 					if is_direct_array_access {
 						g.write(')((${elem_type_str}*)')
 					} else {
@@ -484,7 +484,7 @@ fn (mut g Gen) index_of_map(node ast.IndexExpr, sym ast.TypeSymbol) {
 			if g.is_fn_index_call {
 				if val_sym.info is ast.FnType {
 					g.write('((')
-					g.write_fn_ptr_decl(&val_sym.info, '')
+					g.write_fn_ptr_decl(&val_sym.info, '', true)
 					g.write(')(*(voidptr*)map_get(')
 					is_fn_last_index_call = true
 					g.is_fn_index_call = false
diff --git a/vlib/v/tests/options/option_fn_voidptr_test.v b/vlib/v/tests/options/option_fn_voidptr_test.v
new file mode 100644
index 00000000000000..34f7aa7de56cb6
--- /dev/null
+++ b/vlib/v/tests/options/option_fn_voidptr_test.v
@@ -0,0 +1,18 @@
+struct Foo {
+mut:
+	func ?fn (voidptr) = unsafe { nil }
+}
+
+fn callback(foo &Foo) {
+}
+
+fn test_main() {
+	t := Foo{
+		func: callback
+	}
+	assert t.func? == callback
+
+	mut a := Foo{}
+	a.func = callback
+	assert a.func? == callback
+}