diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c
index 737d21da5a78c4c85eef302f8e35d8146f945439..8c14c179f33d42c128d29c55834ccc2109b2be46 100644
--- a/src/util/vircgroup.c
+++ b/src/util/vircgroup.c
@@ -537,7 +537,7 @@ 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;