diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c
index 6998f13aa4f56914254afe13649d41f754183c49..fef18b1994d3c68d60bdca29c5f7558dc9e62c7f 100644
--- a/src/util/vircgroup.c
+++ b/src/util/vircgroup.c
@@ -366,7 +366,7 @@ static int virCgroupGetValueStr(virCgroupPtr group,
         VIR_DEBUG("Failed to read %s: %m\n", keypath);
     } else {
         /* Terminated with '\n' has sometimes harmful effects to the caller */
-        if ((*value)[rc - 1] == '\n')
+        if (rc > 0 && (*value)[rc - 1] == '\n')
             (*value)[rc - 1] = '\0';
 
         rc = 0;