diff --git a/Makefile b/Makefile
index 281dfef..eeda1f8 100644
--- a/Makefile
+++ b/Makefile
@@ -30,7 +30,7 @@ m16vm : vm/vm.o vm/cpu.o vm/mm.o vm/instr_decode.o \
 
 m16as : as/as.o as/parser.o as/lexer.o \
 	as/codegen.o as/symtab.o \
-	as/ast.o as/asm_error.o lib/libm16.a
+	as/ast.o lib/libm16.a
 	$(LD) $(LDFLAGS) -o $@ $^
 
 lib/libm16.a : lib/vector.o lib/error.o
diff --git a/as/asm_error.c b/as/asm_error.c
deleted file mode 100644
index 455e423..0000000
--- a/as/asm_error.c
+++ /dev/null
@@ -1,35 +0,0 @@
-/* asm_error.c
- *
- *   Copyright (C) 2018-2019   Henrik Hautakoski <henrik.hautakoski@gmail.com>
- *
- *   This program is free software; you can redistribute it and/or modify
- *   it under the terms of the GNU General Public License as published by
- *   the Free Software Foundation; either version 2 of the License, or
- *   (at your option) any later version.
- *
- *   This program is distributed in the hope that it will be useful,
- *   but WITHOUT ANY WARRANTY; without even the implied warranty of
- *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *   GNU General Public License for more details.
- *
- *   You should have received a copy of the GNU General Public License
- *   along with this program; if not, write to the Free Software
- *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
- *   MA 02110-1301, USA.
- */
-#include <stdio.h>
-#include <stdarg.h>
-#include "error.h"
-#include "asm_error.h"
-
-void asm_warn(int lineno, const char *message, ...) {
-
-	fprintf(stderr, "Line %i: ", lineno);
-	warn(message);
-}
-
-int asm_error(int lineno, const char *message, ...) {
-
-	fprintf(stderr, "Line %i: ", lineno);
-	return error(message);
-}
diff --git a/as/asm_error.h b/as/asm_error.h
index 4aa3d7a..950687c 100644
--- a/as/asm_error.h
+++ b/as/asm_error.h
@@ -22,8 +22,10 @@
 
 #include <error.h>
 
-void asm_warn(int lineno, const char *message, ...);
+#define asm_warn(lineno, msg, ...) \
+	warn("Line: %i " msg, lineno, ##__VA_ARGS__)
 
-int asm_error(int lineno, const char *message, ...);
+#define asm_error(lineno, msg, ...) \
+	error("Line: %i " msg, lineno, ##__VA_ARGS__)
 
 #endif /* ASM_ERROR_H */