diff --git a/src/ol/TileCache.js b/src/ol/TileCache.js
index 37f6113df7..57ad1ce3c0 100644
--- a/src/ol/TileCache.js
+++ b/src/ol/TileCache.js
@@ -7,7 +7,7 @@ import {fromKey, getKey} from './tilecoord.js';
 class TileCache extends LRUCache {
 
   /**
-   * @param {!Object<string, import("./TileRange.js").default>} usedTiles Used tiles.
+   * @param {!Object<string, boolean>} usedTiles Used tiles.
    */
   expireCache(usedTiles) {
     while (this.canExpireCache()) {
diff --git a/src/ol/source/BingMaps.js b/src/ol/source/BingMaps.js
index 8ddcdf50ec..b394cbd313 100644
--- a/src/ol/source/BingMaps.js
+++ b/src/ol/source/BingMaps.js
@@ -50,7 +50,7 @@ const TOS_ATTRIBUTION = '<a class="ol-attribution-bing-tos" ' +
 
 /**
  * @typedef {Object} Options
- * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will increase if too small.
+ * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will be ignored if too small.
  * @property {boolean} [hidpi=false] If `true` hidpi tiles will be requested.
  * @property {string} [culture='en-us'] Culture code.
  * @property {string} key Bing Maps API key. Get yours at http://www.bingmapsportal.com/.
diff --git a/src/ol/source/CartoDB.js b/src/ol/source/CartoDB.js
index 29ebf42a66..968b3c467d 100644
--- a/src/ol/source/CartoDB.js
+++ b/src/ol/source/CartoDB.js
@@ -9,7 +9,7 @@ import XYZ from './XYZ.js';
 /**
  * @typedef {Object} Options
  * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
- * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will increase if too small.
+ * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will be ignored if too small.
  * @property {null|string} [crossOrigin] The `crossOrigin` attribute for loaded images.  Note that
  * you must provide a `crossOrigin` value if you want to access pixel data with the Canvas renderer.
  * See https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image for more detail.
diff --git a/src/ol/source/OSM.js b/src/ol/source/OSM.js
index f95f4589a6..b2ecb6c72e 100644
--- a/src/ol/source/OSM.js
+++ b/src/ol/source/OSM.js
@@ -20,7 +20,7 @@ export const ATTRIBUTION = '&#169; ' +
 /**
  * @typedef {Object} Options
  * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
- * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will increase if too small.
+ * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will be ignored if too small.
  * @property {null|string} [crossOrigin='anonymous'] The `crossOrigin` attribute for loaded images.  Note that
  * you must provide a `crossOrigin` value if you want to access pixel data with the Canvas renderer.
  * See https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image for more detail.
diff --git a/src/ol/source/Stamen.js b/src/ol/source/Stamen.js
index d3f768a426..2f8dde8dcd 100644
--- a/src/ol/source/Stamen.js
+++ b/src/ol/source/Stamen.js
@@ -90,7 +90,7 @@ const ProviderConfig = {
 
 /**
  * @typedef {Object} Options
- * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will increase if too small.
+ * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will be ignored if too small.
  * @property {string} layer Layer name.
  * @property {number} [minZoom] Minimum zoom.
  * @property {number} [maxZoom] Maximum zoom.
diff --git a/src/ol/source/Tile.js b/src/ol/source/Tile.js
index baf0386a39..8e5246e816 100644
--- a/src/ol/source/Tile.js
+++ b/src/ol/source/Tile.js
@@ -69,24 +69,21 @@ class TileSource extends Source {
      */
     this.tileGrid = options.tileGrid !== undefined ? options.tileGrid : null;
 
-    let cacheSize = options.cacheSize;
-    if (cacheSize === undefined) {
-      const tileSize = [256, 256];
-      const tileGrid = options.tileGrid;
-      if (tileGrid) {
-        toSize(tileGrid.getTileSize(tileGrid.getMinZoom()), tileSize);
-      }
-      const canUseScreen = typeof screen !== 'undefined';
-      const width = canUseScreen ? (screen.availWidth || screen.width) : 1920;
-      const height = canUseScreen ? (screen.availHeight || screen.height) : 1080;
-      cacheSize = 4 * Math.ceil(width / tileSize[0]) * Math.ceil(height / tileSize[1]);
+    const tileSize = [256, 256];
+    const tileGrid = options.tileGrid;
+    if (tileGrid) {
+      toSize(tileGrid.getTileSize(tileGrid.getMinZoom()), tileSize);
     }
+    const canUseScreen = typeof screen !== 'undefined';
+    const width = canUseScreen ? (screen.availWidth || screen.width) : 1920;
+    const height = canUseScreen ? (screen.availHeight || screen.height) : 1080;
+    const minCacheSize = 4 * Math.ceil(width / tileSize[0]) * Math.ceil(height / tileSize[1]);
 
     /**
      * @protected
      * @type {import("../TileCache.js").default}
      */
-    this.tileCache = new TileCache(cacheSize);
+    this.tileCache = new TileCache(Math.max(minCacheSize, options.cacheSize || 0));
 
     /**
      * @protected
@@ -125,7 +122,7 @@ class TileSource extends Source {
 
   /**
    * @param {import("../proj/Projection.js").default} projection Projection.
-   * @param {!Object<string, import("../TileRange.js").default>} usedTiles Used tiles.
+   * @param {!Object<string, boolean>} usedTiles Used tiles.
    */
   expireCache(projection, usedTiles) {
     const tileCache = this.getTileCacheForProjection(projection);
diff --git a/src/ol/source/TileArcGISRest.js b/src/ol/source/TileArcGISRest.js
index 5e81b927d6..cd347f3c5d 100644
--- a/src/ol/source/TileArcGISRest.js
+++ b/src/ol/source/TileArcGISRest.js
@@ -13,7 +13,7 @@ import {appendParams} from '../uri.js';
 /**
  * @typedef {Object} Options
  * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
- * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will increase if too small.
+ * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will be ignored if too small.
  * @property {null|string} [crossOrigin] The `crossOrigin` attribute for loaded images.  Note that
  * you must provide a `crossOrigin` value if you want to access pixel data with the Canvas renderer.
  * See https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image for more detail.
diff --git a/src/ol/source/TileImage.js b/src/ol/source/TileImage.js
index ac4ccf709e..7e32dd149b 100644
--- a/src/ol/source/TileImage.js
+++ b/src/ol/source/TileImage.js
@@ -17,7 +17,7 @@ import {getForProjection as getTileGridForProjection} from '../tilegrid.js';
  * @typedef {Object} Options
  * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
  * @property {boolean} [attributionsCollapsible=true] Attributions are collapsible.
- * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will increase if too small.
+ * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will be ignored if too small.
  * @property {null|string} [crossOrigin] The `crossOrigin` attribute for loaded images.  Note that
  * you must provide a `crossOrigin` value if you want to access pixel data with the Canvas renderer.
  * See https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image for more detail.
diff --git a/src/ol/source/TileJSON.js b/src/ol/source/TileJSON.js
index 6fe4877095..90887a2312 100644
--- a/src/ol/source/TileJSON.js
+++ b/src/ol/source/TileJSON.js
@@ -39,7 +39,7 @@ import {createXYZ, extentFromProjection} from '../tilegrid.js';
 /**
  * @typedef {Object} Options
  * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
- * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will increase if too small.
+ * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will be ignored if too small.
  * @property {null|string} [crossOrigin] The `crossOrigin` attribute for loaded images.  Note that
  * you must provide a `crossOrigin` value if you want to access pixel data with the Canvas renderer.
  * See https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image for more detail.
diff --git a/src/ol/source/TileWMS.js b/src/ol/source/TileWMS.js
index 513e7ae132..9ee929b63c 100644
--- a/src/ol/source/TileWMS.js
+++ b/src/ol/source/TileWMS.js
@@ -20,7 +20,7 @@ import {appendParams} from '../uri.js';
 /**
  * @typedef {Object} Options
  * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
- * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will increase if too small.
+ * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will be ignored if too small.
  * @property {null|string} [crossOrigin] The `crossOrigin` attribute for loaded images.  Note that
  * you must provide a `crossOrigin` value if you want to access pixel data with the Canvas renderer.
  * See https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image for more detail.
diff --git a/src/ol/source/VectorTile.js b/src/ol/source/VectorTile.js
index 737883fadb..42e4a1f4b9 100644
--- a/src/ol/source/VectorTile.js
+++ b/src/ol/source/VectorTile.js
@@ -227,6 +227,15 @@ class VectorTile extends UrlTile {
     this.sourceTileCache.clear();
   }
 
+  /**
+   * @param {import("../proj/Projection.js").default} projection Projection.
+   * @param {!Object<string, boolean>} usedTiles Used tiles.
+   */
+  expireCache(projection, usedTiles) {
+    super.expireCache(projection, usedTiles);
+    this.sourceTileCache.expireCache({});
+  }
+
   /**
    * @param {number} pixelRatio Pixel ratio.
    * @param {import("../proj/Projection").default} projection Projection.
@@ -328,7 +337,6 @@ class VectorTile extends UrlTile {
         tile.sourceTiles = sourceTiles;
       }
     }
-    this.sourceTileCache.expireCache({});
     return sourceTiles;
   }
 
diff --git a/src/ol/source/WMTS.js b/src/ol/source/WMTS.js
index 603bc78e80..c8b11c9c32 100644
--- a/src/ol/source/WMTS.js
+++ b/src/ol/source/WMTS.js
@@ -15,7 +15,7 @@ import {appendParams} from '../uri.js';
 /**
  * @typedef {Object} Options
  * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
- * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will increase if too small.
+ * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will be ignored if too small.
  * @property {null|string} [crossOrigin] The `crossOrigin` attribute for loaded images.  Note that
  * you must provide a `crossOrigin` value if you want to access pixel data with the Canvas renderer.
  * See https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image for more detail.
diff --git a/src/ol/source/XYZ.js b/src/ol/source/XYZ.js
index 638bf5eb24..85b4ae595e 100644
--- a/src/ol/source/XYZ.js
+++ b/src/ol/source/XYZ.js
@@ -9,7 +9,7 @@ import {createXYZ, extentFromProjection} from '../tilegrid.js';
  * @typedef {Object} Options
  * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
  * @property {boolean} [attributionsCollapsible=true] Attributions are collapsible.
- * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will increase if too small.
+ * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will be ignored if too small.
  * @property {null|string} [crossOrigin] The `crossOrigin` attribute for loaded images.  Note that
  * you must provide a `crossOrigin` value if you want to access pixel data with the Canvas renderer.
  * See https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image for more detail.
diff --git a/src/ol/source/Zoomify.js b/src/ol/source/Zoomify.js
index 509a7e0ae2..23cb232203 100644
--- a/src/ol/source/Zoomify.js
+++ b/src/ol/source/Zoomify.js
@@ -80,7 +80,7 @@ export class CustomTile extends ImageTile {
 /**
  * @typedef {Object} Options
  * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
- * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will increase if too small.
+ * @property {number} [cacheSize] Tile cache size. The default depends on the screen size. Will be ignored if too small.
  * @property {null|string} [crossOrigin] The `crossOrigin` attribute for loaded images.  Note that
  * you must provide a `crossOrigin` value  you want to access pixel data with the Canvas renderer.
  * See https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image for more detail.
diff --git a/test/spec/ol/source/tile.test.js b/test/spec/ol/source/tile.test.js
index f92cb9106b..d9db390d97 100644
--- a/test/spec/ol/source/tile.test.js
+++ b/test/spec/ol/source/tile.test.js
@@ -63,13 +63,19 @@ describe('ol.source.Tile', function() {
       const source = new TileSource({});
       expect(source.tileCache.highWaterMark).to.be(4 * Math.ceil(screen.availWidth / 256) * Math.ceil(screen.availHeight / 256));
     });
+    it('ignores a cache size that is too small', function() {
+      const source = new TileSource({
+        cacheSize: 1
+      });
+      expect(source.tileCache.highWaterMark).to.be(4 * Math.ceil(screen.availWidth / 256) * Math.ceil(screen.availHeight / 256));
+    });
     it('sets a custom cache size', function() {
       const projection = getProjection('EPSG:4326');
       const source = new TileSource({
         projection: projection,
-        cacheSize: 42
+        cacheSize: 442
       });
-      expect(source.getTileCacheForProjection(projection).highWaterMark).to.be(42);
+      expect(source.getTileCacheForProjection(projection).highWaterMark).to.be(442);
     });
   });
 
diff --git a/test/spec/ol/source/tileimage.test.js b/test/spec/ol/source/tileimage.test.js
index cb9b85884c..b5a324ea0a 100644
--- a/test/spec/ol/source/tileimage.test.js
+++ b/test/spec/ol/source/tileimage.test.js
@@ -26,9 +26,9 @@ describe('ol.source.TileImage', function() {
 
   describe('#getTileCacheForProjection', function() {
     it('uses the cacheSize for reprojected tile caches', function() {
-      const source = createSource(undefined, undefined, 42);
+      const source = createSource(undefined, undefined, 442);
       const tileCache = source.getTileCacheForProjection(getProjection('EPSG:4326'));
-      expect(tileCache.highWaterMark).to.be(42);
+      expect(tileCache.highWaterMark).to.be(442);
       expect(tileCache).to.not.equal(source.getTileCacheForProjection(source.getProjection()));
     });
   });