diff --git a/src/config.c b/src/config.c
index 1990318..0c7e5af 100644
--- a/src/config.c
+++ b/src/config.c
@@ -3,12 +3,22 @@
 #include <errno.h>
 #include <string.h>
 #include <stdio.h>
+#include <stdarg.h>
 #include <stdlib.h>
 
 #include "config.h"
 
 enum { bufsize = 1024 };
 
+int
+oal_error(oal_config_t * const c, const char *fmt, ...) {
+  va_list args;
+  va_start(args, fmt);
+  vsnprintf(c->error, sizeof(c->error), fmt, args);
+  va_end(args);
+  return 1;
+}
+
 int parse_config(oal_config_t * const config, const char *file) {
   FILE *f;
   unsigned short linenum = 0;
diff --git a/src/config.h b/src/config.h
index 5c20441..a059cee 100644
--- a/src/config.h
+++ b/src/config.h
@@ -12,6 +12,9 @@ typedef struct {
   char    error[1024];   /** parser error */
 } oal_config_t;
 
+int oal_error(oal_config_t * const c, const char *fmt, ...)
+__attribute__ ((format (printf, 2, 3)));
+
 int parse_config(oal_config_t * const config, const char *file);
 int check_config(oal_config_t * const config);