diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index f4a2bc803c..e1e8787ce7 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -8340,18 +8340,22 @@ fn (mut c Checker) fn_decl(mut node ast.FnDecl) {
 	}
 	if node.language == .v {
 		// Make sure all types are valid
-		for arg in node.params {
-			c.ensure_type_exists(arg.typ, arg.type_pos) or { return }
-			if !arg.typ.is_ptr() { // value parameter, i.e. on stack - check for `[heap]`
-				arg_typ_sym := c.table.get_type_symbol(arg.typ)
+		for mut param in node.params {
+			c.ensure_type_exists(param.typ, param.type_pos) or { return }
+			if !param.typ.is_ptr() { // value parameter, i.e. on stack - check for `[heap]`
+				arg_typ_sym := c.table.get_type_symbol(param.typ)
 				if arg_typ_sym.kind == .struct_ {
 					info := arg_typ_sym.info as ast.Struct
 					if info.is_heap { // set auto_heap to promote value parameter
-						mut v := node.scope.find_var(arg.name) or { continue }
+						mut v := node.scope.find_var(param.name) or { continue }
 						v.is_auto_heap = true
 					}
 				}
 			}
+			if c.pref.translated && node.is_variadic && node.params.len == 1 && param.typ.is_ptr() {
+				// TODO c2v hack to fix `(const char *s, ...)`
+				param.typ = ast.int_type.to_ptr()
+			}
 		}
 	}
 	if node.language == .v && node.name.after_char(`.`) == 'init' && !node.is_method
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 2a04780429..1e8593854d 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -1533,7 +1533,7 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 			}
 		}
 		ast.FnDecl {
-			g.process_fn_decl(node)
+			g.fn_decl(node)
 		}
 		ast.ForCStmt {
 			prev_branch_parent_pos := g.branch_parent_pos
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index aa7bf401c0..2cf6426e7b 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -28,7 +28,7 @@ fn (mut g Gen) is_used_by_main(node ast.FnDecl) bool {
 	return is_used_by_main
 }
 
-fn (mut g Gen) process_fn_decl(node ast.FnDecl) {
+fn (mut g Gen) fn_decl(node ast.FnDecl) {
 	if !g.is_used_by_main(node) {
 		return
 	}
@@ -43,6 +43,11 @@ fn (mut g Gen) process_fn_decl(node ast.FnDecl) {
 	mut skip := false
 	pos := g.out.len
 	should_bundle_module := util.should_bundle_module(node.mod)
+	/*
+	if node.name.contains('i_error') {
+		println(g.table.type_str(node.params[0].typ))
+	}
+	*/
 	if g.pref.build_mode == .build_module {
 		// if node.name.contains('parse_text') {
 		// println('!!! $node.name mod=$node.mod, built=$g.module_built')
@@ -77,13 +82,13 @@ fn (mut g Gen) process_fn_decl(node ast.FnDecl) {
 	if node.is_main {
 		g.has_main = true
 	}
-	if node.name == 'backtrace' || node.name == 'backtrace_symbols'
-		|| node.name == 'backtrace_symbols_fd' {
+	is_backtrace := node.name.starts_with('backtrace') // TODO PERF remove this from here
+		&& node.name in ['backtrace_symbols', 'backtrace', 'backtrace_symbols_fd']
+	if is_backtrace {
 		g.write('\n#ifndef __cplusplus\n')
 	}
 	g.gen_fn_decl(node, skip)
-	if node.name == 'backtrace' || node.name == 'backtrace_symbols'
-		|| node.name == 'backtrace_symbols_fd' {
+	if is_backtrace {
 		g.write('\n#endif\n')
 	}
 	g.fn_decl = keep_fn_decl
@@ -454,7 +459,7 @@ fn (mut g Gen) gen_anon_fn_decl(mut node ast.AnonFn) {
 	pos := g.out.len
 	was_anon_fn := g.anon_fn
 	g.anon_fn = true
-	g.process_fn_decl(node.decl)
+	g.fn_decl(node.decl)
 	g.anon_fn = was_anon_fn
 	builder.write_string(g.out.cut_to(pos))
 	g.anon_fn_definitions << builder.str()