diff --git a/CHANGES b/CHANGES
index 84a1abd7..4c248eb7 100644
--- a/CHANGES
+++ b/CHANGES
@@ -6,6 +6,7 @@ SVN-HEAD
               Add support for current sensors
               Fix error propagation during expression evaluation
               Detect excessive recursion depth during expression eval (#2365)
+              Return a string rather than NULL for unknown errors
   lm_sensors.init: Support new format of /etc/sysconfig/lm_sensors (#2246)
                    Drop support for kernels 2.4 and earlier
   lm_sensors.init.suse: Delete (actual SuSE script is much different)
diff --git a/lib/error.c b/lib/error.c
index 7472c59b..8ddaa0cf 100644
--- a/lib/error.c
+++ b/lib/error.c
@@ -33,7 +33,7 @@ void (*sensors_fatal_error) (const char *proc, const char *err) =
 						sensors_default_fatal_error;
 
 static const char *errorlist[] = {
-	/* Invalid error code    */ NULL,
+	/* Invalid error code    */ "Unknown error",
 	/* SENSORS_ERR_WILDCARDS */ "Wildcard found in chip name",
 	/* SENSORS_ERR_NO_ENTRY  */ "No such subfeature known",
 	/* SENSORS_ERR_ACCESS_R  */ "Can't read",