diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 01d168eb87..e827b2a810 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -18453,7 +18453,9 @@ virDomainCachetuneDefParse(virDomainDefPtr def,
 
     /* We need to limit the bitmap to number of vCPUs.  If there's nothing left,
      * then we can just clean up and return 0 immediately */
-    virBitmapShrink(vcpus, def->maxvcpus);
+    if (virBitmapShrink(vcpus, def->maxvcpus) < 0)
+        goto cleanup;
+
     if (virBitmapIsAllClear(vcpus)) {
         ret = 0;
         goto cleanup;
diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c
index b2c5c7a6a5..33cae2f305 100644
--- a/src/util/virbitmap.c
+++ b/src/util/virbitmap.c
@@ -1201,21 +1201,35 @@ virBitmapSubtract(virBitmapPtr a,
 /**
  * virBitmapShrink:
  * @map: Pointer to bitmap
- * @b: last bit position to be excluded from bitmap
+ * @b: Size to reduce the bitmap to
  *
- * Resizes the bitmap so that no more than @b bits will fit into it.  Nothing
- * will change if the size is already smaller than @b.
- *
- * NB: Does not adjust the map->map_len so that a subsequent virBitmapExpand
- * doesn't necessarily need to reallocate.
+ * Reduces the bitmap to size @b.  Nothing will change if the size is already
+ * smaller than or equal to @b.
  */
-void
+int
 virBitmapShrink(virBitmapPtr map,
                 size_t b)
 {
+    size_t nl = 0;
+    size_t nb = 0;
+
     if (!map)
-        return;
+        return 0;
 
     if (map->max_bit >= b)
         map->max_bit = b;
+
+    nl = map->max_bit / VIR_BITMAP_BITS_PER_UNIT;
+    nb = map->max_bit % VIR_BITMAP_BITS_PER_UNIT;
+    map->map[nl] &= ((1UL << nb) - 1);
+
+    nl++;
+    if (nl == map->map_len)
+        return 0;
+
+    if (VIR_REALLOC_N(map->map, nl) < 0)
+        return -1;
+
+    map->map_len = nl;
+    return 0;
 }
diff --git a/src/util/virbitmap.h b/src/util/virbitmap.h
index 2464814055..5a3362a19f 100644
--- a/src/util/virbitmap.h
+++ b/src/util/virbitmap.h
@@ -153,6 +153,6 @@ void virBitmapIntersect(virBitmapPtr a, virBitmapPtr b)
 void virBitmapSubtract(virBitmapPtr a, virBitmapPtr b)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
-void virBitmapShrink(virBitmapPtr map, size_t b);
+int virBitmapShrink(virBitmapPtr map, size_t b);
 
 #endif
diff --git a/src/util/virresctrl.c b/src/util/virresctrl.c
index 70426199ce..ef388757a7 100644
--- a/src/util/virresctrl.c
+++ b/src/util/virresctrl.c
@@ -941,7 +941,8 @@ virResctrlAllocParseProcessCache(virResctrlInfoPtr resctrl,
     if (!mask)
         return -1;
 
-    virBitmapShrink(mask, resctrl->levels[level]->types[type]->bits);
+    if (virBitmapShrink(mask, resctrl->levels[level]->types[type]->bits) < 0)
+        goto cleanup;
 
     if (virResctrlAllocUpdateMask(alloc, level, type, cache_id, mask) < 0)
         goto cleanup;
diff --git a/tests/virbitmaptest.c b/tests/virbitmaptest.c
index 9c0ffe70cb..fffecdf1f6 100644
--- a/tests/virbitmaptest.c
+++ b/tests/virbitmaptest.c
@@ -656,6 +656,14 @@ test12(const void *opaque ATTRIBUTE_UNUSED)
 
     TEST_MAP(1024, "34,1023");
 
+    if (virBitmapShrink(map, 35) < 0)
+        goto cleanup;
+    TEST_MAP(35, "34");
+
+    if (virBitmapShrink(map, 34) < 0)
+        goto cleanup;
+    TEST_MAP(34, "");
+
     ret = 0;
 
  cleanup: