diff --git a/sys/include/net/gnrc/sixlowpan/frag/vrb.h b/sys/include/net/gnrc/sixlowpan/frag/vrb.h
index e21347e729..3bb859195a 100644
--- a/sys/include/net/gnrc/sixlowpan/frag/vrb.h
+++ b/sys/include/net/gnrc/sixlowpan/frag/vrb.h
@@ -25,6 +25,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#include "kernel_defines.h"
 #include "net/gnrc/netif.h"
 #include "net/gnrc/sixlowpan/config.h"
 #ifdef MODULE_GNRC_SIXLOWPAN_FRAG
@@ -123,9 +124,9 @@ gnrc_sixlowpan_frag_vrb_t *gnrc_sixlowpan_frag_vrb_get(
  */
 static inline void gnrc_sixlowpan_frag_vrb_rm(gnrc_sixlowpan_frag_vrb_t *vrb)
 {
-#ifdef MODULE_GNRC_SIXLOWPAN_FRAG
-    gnrc_sixlowpan_frag_rb_base_rm(&vrb->super);
-#endif  /* MODULE_GNRC_SIXLOWPAN_FRAG */
+    if (IS_USED(MODULE_GNRC_SIXLOWPAN_FRAG_RB)) {
+        gnrc_sixlowpan_frag_rb_base_rm(&vrb->super);
+    }
     vrb->super.src_len = 0;
 }
 
diff --git a/sys/net/gnrc/network_layer/sixlowpan/frag/rb/gnrc_sixlowpan_frag_rb.c b/sys/net/gnrc/network_layer/sixlowpan/frag/rb/gnrc_sixlowpan_frag_rb.c
index f043ba6b7a..a2fe7c937a 100644
--- a/sys/net/gnrc/network_layer/sixlowpan/frag/rb/gnrc_sixlowpan_frag_rb.c
+++ b/sys/net/gnrc/network_layer/sixlowpan/frag/rb/gnrc_sixlowpan_frag_rb.c
@@ -302,6 +302,12 @@ static int _rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
         memcpy(((uint8_t *)entry->pkt->data) + offset, data,
                frag_size);
     }
+    else {
+        /* no space left in rbuf interval buffer*/
+        gnrc_pktbuf_release(entry->pkt);
+        gnrc_sixlowpan_frag_rb_remove(entry);
+        res = RBUF_ADD_ERROR;
+    }
     /* no errors and not consumed => release packet */
     gnrc_pktbuf_release(pkt);
     return res;
diff --git a/sys/net/gnrc/network_layer/sixlowpan/frag/vrb/gnrc_sixlowpan_frag_vrb.c b/sys/net/gnrc/network_layer/sixlowpan/frag/vrb/gnrc_sixlowpan_frag_vrb.c
index 6d42cc51ad..dac87c3984 100644
--- a/sys/net/gnrc/network_layer/sixlowpan/frag/vrb/gnrc_sixlowpan_frag_vrb.c
+++ b/sys/net/gnrc/network_layer/sixlowpan/frag/vrb/gnrc_sixlowpan_frag_vrb.c
@@ -83,6 +83,34 @@ gnrc_sixlowpan_frag_vrb_t *gnrc_sixlowpan_frag_vrb_add(
                                              vrbe->super.dst_len,
                                              addr_str), vrbe->out_tag);
             }
+            /* _equal_index() => append intervals of `base`, so they don't get
+             * lost. We use append, so we don't need to change base! */
+            else if (base->ints != NULL) {
+                gnrc_sixlowpan_frag_rb_int_t *tmp = vrbe->super.ints;
+
+                if (tmp != base->ints) {
+                    /* base->ints is not already vrbe->super.ints */
+                    if (tmp != NULL) {
+                        /* iterate before appending and check if `base->ints` is
+                         * not already part of list */
+                        while (tmp->next != NULL) {
+                            if (tmp == base->ints) {
+                                tmp = NULL;
+                            }
+                            /* cppcheck-suppress nullPointer
+                             * (reason: possible bug in cppcheck, tmp can't
+                             * clearly be a NULL pointer here) */
+                            tmp = tmp->next;
+                        }
+                        if (tmp != NULL) {
+                            tmp->next = base->ints;
+                        }
+                    }
+                    else {
+                        vrbe->super.ints = base->ints;
+                    }
+                }
+            }
             break;
         }
     }