diff --git a/core/net/link-stats.c b/core/net/link-stats.c
index 2312f5b23..37e764458 100644
--- a/core/net/link-stats.c
+++ b/core/net/link-stats.c
@@ -55,13 +55,13 @@
 
 /* EWMA (exponential moving average) used to maintain statistics over time */
 #define EWMA_SCALE            100
-#define EWMA_ALPHA             10
+#define EWMA_ALPHA             15
 #define EWMA_BOOTSTRAP_ALPHA   30
 
 /* ETX fixed point divisor. 128 is the value used by RPL (RFC 6551 and RFC 6719) */
 #define ETX_DIVISOR     LINK_STATS_ETX_DIVISOR
 /* Number of Tx used to update the ETX EWMA in case of no-ACK */
-#define ETX_NOACK_PENALTY                   16
+#define ETX_NOACK_PENALTY                   10
 /* Initial ETX value */
 #define ETX_INIT                             2
 
diff --git a/core/net/rpl/rpl-mrhof.c b/core/net/rpl/rpl-mrhof.c
index fde280110..a3f4d2b87 100644
--- a/core/net/rpl/rpl-mrhof.c
+++ b/core/net/rpl/rpl-mrhof.c
@@ -71,8 +71,8 @@
 #endif /* RPL_MRHOF_CONF_SQUARED_ETX */
 
 /* Configuration parameters of RFC6719. Reject parents that have a higher
- * link metric than the following. We use the default values from the RFC. */
-#define MAX_LINK_METRIC      512   /* Eq ETX of 4 */
+ * link metric than the following. The default value is 512 but we use 1024. */
+#define MAX_LINK_METRIC     1024   /* Eq ETX of 8 */
 /* Reject parents that have a higher path cost than the following. */
 #define MAX_PATH_COST			 32768   /* Eq path ETX of 256 */
 /* Hysteresis of MRHOF: the rank must differ more than PARENT_SWITCH_THRESHOLD_DIV
@@ -187,19 +187,14 @@ best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
   int p1_is_acceptable;
   int p2_is_acceptable;
 
-  if(p1 == NULL || p2 == NULL) {
-    /* Return non-null parent if any */
-    return p1 == NULL ? p2 : p1;
-  }
+  p1_is_acceptable = p1 != NULL && parent_is_acceptable(p1);
+  p2_is_acceptable = p2 != NULL && parent_is_acceptable(p2);
 
-  p1_is_acceptable = parent_is_acceptable(p1);
-  p2_is_acceptable = parent_is_acceptable(p2);
-  /* Is only one parent is acceptable, select it. If both are acceptable, or
-   * both non-acceptable, proceed to traditional parent comparison. This is a
-   * slight departure from the standard but allows to keep connectivity even
-   * all neighbors appear to have a bad link. */
-  if(p1_is_acceptable != p2_is_acceptable) {
-    return p1_is_acceptable ? p1 : p2;
+  if(!p1_is_acceptable) {
+    return p2_is_acceptable ? p2 : NULL;
+  }
+  if(!p2_is_acceptable) {
+    return p1_is_acceptable ? p1 : NULL;
   }
 
   dag = p1->dag; /* Both parents are in the same DAG. */
diff --git a/core/net/rpl/rpl-of0.c b/core/net/rpl/rpl-of0.c
index 2fcb17a07..84b14d1ba 100644
--- a/core/net/rpl/rpl-of0.c
+++ b/core/net/rpl/rpl-of0.c
@@ -145,19 +145,14 @@ best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
   int p1_is_acceptable;
   int p2_is_acceptable;
 
-  if(p1 == NULL || p2 == NULL) {
-    /* Return non-null parent if any */
-    return p1 == NULL ? p2 : p1;
-  }
+  p1_is_acceptable = p1 != NULL && parent_is_acceptable(p1);
+  p2_is_acceptable = p2 != NULL && parent_is_acceptable(p2);
 
-  p1_is_acceptable = parent_is_acceptable(p1);
-  p2_is_acceptable = parent_is_acceptable(p2);
-  /* Is only one parent is acceptable, select it. If both are acceptable, or
-   * both non-acceptable, proceed to traditional parent comparison. This is a
-   * slight departure from the standard but allows to keep connectivity even
-   * all neighbors appear to have a bad link. */
-  if(p1_is_acceptable != p2_is_acceptable) {
-    return p1_is_acceptable ? p1 : p2;
+  if(!p1_is_acceptable) {
+    return p2_is_acceptable ? p2 : NULL;
+  }
+  if(!p2_is_acceptable) {
+    return p1_is_acceptable ? p1 : NULL;
   }
 
   dag = p1->dag; /* Both parents are in the same DAG. */