diff --git a/src/config.c b/src/config.c
index 0c7e5af..fc80d79 100644
--- a/src/config.c
+++ b/src/config.c
@@ -29,10 +29,8 @@ int parse_config(oal_config_t * const config, const char *file) {
   assert(config != NULL);
   assert(file   != NULL);
 
-  if ((f = fopen(file, "r")) == NULL) {
-    snprintf(config->error, sizeof(config->error), "can't open file: %s", strerror(errno));
-    return 1;
-  }
+  if ((f = fopen(file, "r")) == NULL)
+    return oal_error(config, "can't open file: %s", strerror(errno));
 
   while (fgets(buf, bufsize, f)) {
     linenum++;
@@ -44,25 +42,19 @@ int parse_config(oal_config_t * const config, const char *file) {
       continue; /* ignore comments */
     if (strlen(key) == 0)
       continue; /* ignore empty lines */
-    if (!isalpha(*key)) {
-      snprintf(config->error, sizeof(config->error), "can't parse line %d", linenum);
-      return 1;
-    }
+    if (!isalpha(*key))
+      return oal_error(config, "can't parse line %d", linenum);
     /* find start of value */
     value = key;
     while(*value && !isspace(*value))
       value++;
-    if (!isspace(*value)) {
-      snprintf(config->error, sizeof(config->error), "can't find value at line %d", linenum);
-      return 1;
-    }
+    if (!isspace(*value))
+      return oal_error(config, "can't find value at line %d", linenum);
     *value = '\0', value += 1;
     while (isspace(*value))
       value++;
-    if (!*value) {
-      snprintf(config->error, sizeof(config->error), "can't find value at line %d", linenum);
-      return 1;
-    }
+    if (!*value)
+      return oal_error(config, "can't find value at line %d", linenum);
     /* strip trailing spaces and newline */
     valsize = strnlen(value, bufsize - (value - buf));
     while (valsize && isspace(value[valsize - 1])) {
@@ -90,10 +82,8 @@ int parse_config(oal_config_t * const config, const char *file) {
     } else
     if (strncmp(key, "userfilter", 10) == 0) {
       config->userfilter = strndup(value, valsize);
-    } else
-    {
-      snprintf(config->error, sizeof(config->error), "unknown key '%s' at line %d", key, linenum);
-      return 1;
+    } else {
+      return oal_error(config, "unknown key '%s' at line %d", key, linenum);
     }
   }
 
@@ -103,22 +93,14 @@ int parse_config(oal_config_t * const config, const char *file) {
 int check_config(oal_config_t * const config) {
   assert(config != NULL);
 
-  if (!config->bindurls) {
-    snprintf(config->error, sizeof(config->error), "'bindurls' not set in config");
-    return 1;
-  }
-  if (!config->basedn) {
-    snprintf(config->error, sizeof(config->error), "'basedn' not set in config");
-    return 1;
-  }
-  if (!config->userfilter) {
-    snprintf(config->error, sizeof(config->error), "'userfilter' not set in config");
-    return 1;
-  }
-  if (config->binddn && !config->bindpass) {
-    snprintf(config->error, sizeof(config->error), "'bindn' set, but 'bindpass' missing in config");
-    return 1;
-  }
+  if (!config->bindurls)
+    return oal_error(config, "'bindurls' not set in config");
+  if (!config->basedn)
+    return oal_error(config, "'basedn' not set in config");
+  if (!config->userfilter)
+    return oal_error(config, "'userfilter' not set in config");
+  if (config->binddn && !config->bindpass)
+    return oal_error(config, "'bindn' set, but 'bindpass' missing in config");
 
   return 0;
 }
diff --git a/src/ldapauth.c b/src/ldapauth.c
index 8cc2396..4f8deef 100644
--- a/src/ldapauth.c
+++ b/src/ldapauth.c
@@ -65,7 +65,7 @@ oal_connect(LDAP ** ld,
   int rc = 0;
 
   if ((rc = ldap_initialize(ld, config->bindurls)) != LDAP_SUCCESS) {
-    snprintf(config->error, sizeof(config->error), "can't connect to ldap server(s): %s", strerror(errno));
+    oal_error(config, "can't connect to ldap server(s): %s", strerror(errno));
     return 1;
   }
 
@@ -76,38 +76,38 @@ oal_connect(LDAP ** ld,
 
   /* hardcoded options */
   if (ldap_set_option(*ld, LDAP_OPT_PROTOCOL_VERSION, &ldapver) != LDAP_OPT_SUCCESS) {
-    snprintf(config->error, sizeof(config->error), "can't set ldap protocol version");
+    oal_error(config, "can't set ldap protocol version");
     return 1;
   }
   if (ldap_set_option(*ld, LDAP_OPT_SIZELIMIT, &sizelimit) != LDAP_OPT_SUCCESS) {
-    snprintf(config->error, sizeof(config->error), "can't set max results limit");
+    oal_error(config, "can't set max results limit");
     return 1;
   }
   if (ldap_set_option(*ld, LDAP_OPT_REFERRALS, LDAP_OPT_OFF) != LDAP_OPT_SUCCESS) {
-    snprintf(config->error, sizeof(config->error), "can't set follow referrals to 'off'");
+    oal_error(config, "can't set follow referrals to 'off'");
     return 1;
   }
   /* timeouts */
   if (ldap_set_option(*ld, LDAP_OPT_NETWORK_TIMEOUT, &tv) != LDAP_OPT_SUCCESS) {
-    snprintf(config->error, sizeof(config->error), "can't set network timeout: %d", config->bindtimeout);
+    oal_error(config, "can't set network timeout: %d", config->bindtimeout);
     return 1;
   }
   if (ldap_set_option(*ld, LDAP_OPT_TIMEOUT,         &tv) != LDAP_OPT_SUCCESS) {
-    snprintf(config->error, sizeof(config->error), "can't set search timeout: %d", config->bindtimeout);
+    oal_error(config, "can't set search timeout: %d", config->bindtimeout);
     return 1;
   }
   if (ldap_set_option(*ld, LDAP_OPT_DEBUG_LEVEL, &ldapdebug) != LDAP_OPT_SUCCESS) {
-    snprintf(config->error, sizeof(config->error), "can't set debug level for ldap conn");
+    oal_error(config, "can't set debug level for ldap conn");
     return 1;
   }
   /* required */
   if (ldap_set_option(*ld, LDAP_OPT_DEFBASE,   config->basedn) != LDAP_OPT_SUCCESS) {
-    snprintf(config->error, sizeof(config->error), "can't set searchbase: %s", config->basedn);
+    oal_error(config, "can't set searchbase: %s", config->basedn);
     return 1;
   }
 
   if ((rc = ldap_simple_bind_s(*ld, binddn, bindpass)) != LDAP_SUCCESS) {
-    snprintf(config->error, sizeof(config->error), "can't bind to ldap server: %s", ldap_err2string(rc));
+    oal_error(config, "can't bind to ldap server: %s", ldap_err2string(rc));
     return 1;
   }
 
@@ -139,12 +139,12 @@ oal_check_cred(oal_config_t * const config,
   assert(password != NULL);
 
   if (oal_ldap_escape(uid, sizeof(uid), username) < 0) {
-    snprintf(config->error, sizeof(config->error), "can't escape username: it's too long");
+    oal_error(config, "can't escape username: it's too long");
     return -1;
   }
 
   if (snprintf(filter, sizeof(filter), config->userfilter, uid, uid) >= (int) sizeof(filter)) {
-    snprintf(config->error, sizeof(config->error), "can't interpolate userfilter: lack of space");
+    oal_error(config, "can't interpolate userfilter: lack of space");
     return -1;
   }
 
@@ -155,21 +155,21 @@ oal_check_cred(oal_config_t * const config,
 
   lrc = ldap_search_s(sld, config->basedn, LDAP_SCOPE_SUBTREE, filter, searchattr, 1, &res);
   if (lrc != LDAP_SUCCESS) {
-    snprintf(config->error, sizeof(config->error), "ldap search failed: %s", ldap_err2string(lrc));
+    oal_error(config, "ldap search failed: %s", ldap_err2string(lrc));
     goto cleanup; /* TODO */
   }
 
   lrc = ldap_count_entries(sld, res);
   if (lrc <= 0) {
     if (lrc == 0) {
-      snprintf(config->error, sizeof(config->error), "user not found");
+      oal_error(config, "user not found");
       rc = 0;
     }
     goto cleanup;
   }
 
   if ((msg = ldap_first_entry(sld, res)) == NULL) {
-    snprintf(config->error, sizeof(config->error), "ldap search found something, but can't get result");
+    oal_error(config, "ldap search found something, but can't get result");
     goto cleanup;
   }
 
@@ -178,7 +178,7 @@ oal_check_cred(oal_config_t * const config,
       continue;
 
     if ((udn = ldap_get_dn(sld, msg)) == NULL || strlen(udn) == 0) {
-      snprintf(config->error, sizeof(config->error), "can't get DN of found user");
+      oal_error(config, "can't get DN of found user");
       break;
     }
 fprintf(stderr, "dn: %s\n", udn);
@@ -188,7 +188,7 @@ fprintf(stderr, "dn: %s\n", udn);
       ldap_unbind(ald);
       break; /* success */
     } else {
-      snprintf(config->error, sizeof(config->error), "password mismatch");
+      oal_error(config, "password mismatch");
       rc = 0;
       break;
     }