diff --git a/epicardium/modules/config.c b/epicardium/modules/config.c
index e00b3bb6086788606b16e36c41fa369dc2aa0aaa..2e741b93ff41907e9ab05e0b9256fbc08e26a390 100644
--- a/epicardium/modules/config.c
+++ b/epicardium/modules/config.c
@@ -517,6 +517,7 @@ int epic_config_set_string(const char *key, const char *value_in)
 		);
 		if (nread == 0) {
 			LOG_DEBUG("card10.cfg", "could not read old value");
+			ret = -EIO;
 			goto complex_out;
 		}