diff --git a/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamExtractor.java b/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamExtractor.java
index 4c2b5a3e1..3aebaee1e 100644
--- a/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamExtractor.java
+++ b/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamExtractor.java
@@ -760,7 +760,8 @@ public class YoutubeStreamExtractor extends StreamExtractor {
     }
 
     private void checkPlayabilityStatus(final JsonObject youtubePlayerResponse,
-                                        JsonObject playabilityStatus) throws ParsingException {
+                                        @Nonnull JsonObject playabilityStatus)
+            throws ParsingException {
         String status = playabilityStatus.getString("status");
         // If status exist, and is not "OK", throw the specific exception based on error message
         // or a ContentNotAvailableException with the reason text if it's an unknown reason.
@@ -871,6 +872,7 @@ public class YoutubeStreamExtractor extends StreamExtractor {
         }
     }
 
+    @Nonnull
     private byte[] createPlayerBodyWithSts(final Localization localization,
                                            final ContentCountry contentCountry,
                                            final String videoId) throws ExtractionException,
@@ -988,6 +990,7 @@ public class YoutubeStreamExtractor extends StreamExtractor {
                 "Could not find deobfuscate function with any of the given patterns.", exception);
     }
 
+    @Nonnull
     private String loadDeobfuscationCode() throws DeobfuscateException {
         try {
             final String deobfuscationFunctionName = getDeobfuscationFuncName(playerCode);
@@ -1115,6 +1118,7 @@ public class YoutubeStreamExtractor extends StreamExtractor {
                 "&sts=" + sts + "&ps=default&gl=US&hl=en";
     }
 
+    @Nonnull
     private Map<String, ItagItem> getItags(final String streamingDataKey,
                                            final ItagItem.ItagType itagTypeWanted)
             throws ParsingException {
@@ -1371,4 +1375,21 @@ public class YoutubeStreamExtractor extends StreamExtractor {
                 nextResponse.getObject("contents").getObject("twoColumnWatchNextResults")
                         .getObject("results").getObject("results").getArray("contents"));
     }
+
+    /**
+     * Reset YouTube deobfuscation code.
+     * <p>
+     * This is needed for mocks in YouTube stream tests, because when they are ran, the
+     * {@code signatureTimestamp} is known (the {@code sts} string) so a different body than the
+     * body present in the mocks is send by the extractor instance. As a result, running all
+     * YouTube stream tests with the MockDownloader (like the CI does) will fail if this method is
+     * not called before fetching the page of a test.
+     * </p>
+     */
+    public static void resetDeobfuscationCode() {
+        cachedDeobfuscationCode = null;
+        playerCode = null;
+        playerJsUrl = null;
+        sts = null;
+    }
 }
diff --git a/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorAgeRestrictedTest.java b/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorAgeRestrictedTest.java
index 180dc173c..8a7b521f7 100644
--- a/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorAgeRestrictedTest.java
+++ b/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorAgeRestrictedTest.java
@@ -6,6 +6,7 @@ import org.schabi.newpipe.extractor.NewPipe;
 import org.schabi.newpipe.extractor.StreamingService;
 import org.schabi.newpipe.extractor.services.DefaultStreamExtractorTest;
 import org.schabi.newpipe.extractor.services.youtube.YoutubeParsingHelper;
+import org.schabi.newpipe.extractor.services.youtube.extractors.YoutubeStreamExtractor;
 import org.schabi.newpipe.extractor.stream.StreamExtractor;
 import org.schabi.newpipe.extractor.stream.StreamType;
 
@@ -28,6 +29,7 @@ public class YoutubeStreamExtractorAgeRestrictedTest extends DefaultStreamExtrac
     public static void setUp() throws Exception {
         YoutubeParsingHelper.resetClientVersionAndKey();
         YoutubeParsingHelper.setNumberGenerator(new Random(1));
+        YoutubeStreamExtractor.resetDeobfuscationCode();
         NewPipe.init(new DownloaderFactory().getDownloader(RESOURCE_PATH + "ageRestricted"));
         extractor = YouTube.getStreamExtractor(URL);
         extractor.fetchPage();
diff --git a/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorControversialTest.java b/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorControversialTest.java
index 360b91960..b0f40a779 100644
--- a/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorControversialTest.java
+++ b/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorControversialTest.java
@@ -7,6 +7,7 @@ import org.schabi.newpipe.extractor.NewPipe;
 import org.schabi.newpipe.extractor.StreamingService;
 import org.schabi.newpipe.extractor.services.DefaultStreamExtractorTest;
 import org.schabi.newpipe.extractor.services.youtube.YoutubeParsingHelper;
+import org.schabi.newpipe.extractor.services.youtube.extractors.YoutubeStreamExtractor;
 import org.schabi.newpipe.extractor.services.youtube.linkHandler.YoutubeStreamLinkHandlerFactory;
 import org.schabi.newpipe.extractor.stream.StreamExtractor;
 import org.schabi.newpipe.extractor.stream.StreamType;
@@ -33,6 +34,7 @@ public class YoutubeStreamExtractorControversialTest extends DefaultStreamExtrac
     public static void setUp() throws Exception {
         YoutubeParsingHelper.resetClientVersionAndKey();
         YoutubeParsingHelper.setNumberGenerator(new Random(1));
+        YoutubeStreamExtractor.resetDeobfuscationCode();
         NewPipe.init(new DownloaderFactory().getDownloader(RESOURCE_PATH + "controversial"));
         extractor = YouTube.getStreamExtractor(URL);
         extractor.fetchPage();
diff --git a/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorDefaultTest.java b/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorDefaultTest.java
index 1fefc8b85..2ce2a8283 100644
--- a/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorDefaultTest.java
+++ b/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorDefaultTest.java
@@ -63,6 +63,7 @@ public class YoutubeStreamExtractorDefaultTest {
         public static void setUp() throws IOException {
             YoutubeParsingHelper.resetClientVersionAndKey();
             YoutubeParsingHelper.setNumberGenerator(new Random(1));
+            YoutubeStreamExtractor.resetDeobfuscationCode();
             NewPipe.init(new DownloaderFactory().getDownloader(RESOURCE_PATH + "notAvailable"));
         }
 
@@ -119,6 +120,7 @@ public class YoutubeStreamExtractorDefaultTest {
         public static void setUp() throws Exception {
             YoutubeParsingHelper.resetClientVersionAndKey();
             YoutubeParsingHelper.setNumberGenerator(new Random(1));
+            YoutubeStreamExtractor.resetDeobfuscationCode();
             NewPipe.init(new DownloaderFactory().getDownloader(RESOURCE_PATH + "pewdiwpie"));
             extractor = YouTube.getStreamExtractor(URL);
             extractor.fetchPage();
@@ -162,6 +164,7 @@ public class YoutubeStreamExtractorDefaultTest {
         public static void setUp() throws Exception {
             YoutubeParsingHelper.resetClientVersionAndKey();
             YoutubeParsingHelper.setNumberGenerator(new Random(1));
+            YoutubeStreamExtractor.resetDeobfuscationCode();
             NewPipe.init(new DownloaderFactory().getDownloader(RESOURCE_PATH + "unboxing"));
             extractor = YouTube.getStreamExtractor(URL);
             extractor.fetchPage();
@@ -215,6 +218,7 @@ public class YoutubeStreamExtractorDefaultTest {
         public static void setUp() throws Exception {
             YoutubeParsingHelper.resetClientVersionAndKey();
             YoutubeParsingHelper.setNumberGenerator(new Random(1));
+            YoutubeStreamExtractor.resetDeobfuscationCode();
             NewPipe.init(new DownloaderFactory().getDownloader(RESOURCE_PATH + "ratingsDisabled"));
             extractor = YouTube.getStreamExtractor(URL);
             extractor.fetchPage();
@@ -252,6 +256,7 @@ public class YoutubeStreamExtractorDefaultTest {
         public static void setUp() throws Exception {
             YoutubeParsingHelper.resetClientVersionAndKey();
             YoutubeParsingHelper.setNumberGenerator(new Random(1));
+            YoutubeStreamExtractor.resetDeobfuscationCode();
             NewPipe.init(new DownloaderFactory().getDownloader(RESOURCE_PATH + "streamSegmentsTagesschau"));
             extractor = YouTube.getStreamExtractor(URL);
             extractor.fetchPage();
@@ -313,6 +318,7 @@ public class YoutubeStreamExtractorDefaultTest {
         public static void setUp() throws Exception {
             YoutubeParsingHelper.resetClientVersionAndKey();
             YoutubeParsingHelper.setNumberGenerator(new Random(1));
+            YoutubeStreamExtractor.resetDeobfuscationCode();
             NewPipe.init(new DownloaderFactory().getDownloader(RESOURCE_PATH + "streamSegmentsMaiLab"));
             extractor = YouTube.getStreamExtractor(URL);
             extractor.fetchPage();
@@ -383,6 +389,7 @@ public class YoutubeStreamExtractorDefaultTest {
             YoutubeParsingHelper.setNumberGenerator(new Random(1));
             NewPipe.init(new DownloaderFactory().getDownloader(RESOURCE_PATH + "publicBroadcast"));
             extractor = YouTube.getStreamExtractor(URL);
+            YoutubeStreamExtractor.resetDeobfuscationCode();
             extractor.fetchPage();
         }
 
@@ -432,6 +439,7 @@ public class YoutubeStreamExtractorDefaultTest {
 
         @BeforeClass
         public static void setUp() throws Exception {
+            YoutubeStreamExtractor.resetDeobfuscationCode();
             NewPipe.init(DownloaderTestImpl.getInstance());
             extractor = (YoutubeStreamExtractor) YouTube
                     .getStreamExtractor("https://www.youtube.com/watch?v=tjz2u2DiveM");
@@ -451,6 +459,7 @@ public class YoutubeStreamExtractorDefaultTest {
 
         @BeforeClass
         public static void setUp() throws Exception {
+            YoutubeStreamExtractor.resetDeobfuscationCode();
             NewPipe.init(DownloaderTestImpl.getInstance());
             extractor = YouTube.getStreamExtractor(URL);
             extractor.fetchPage();
diff --git a/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorLivestreamTest.java b/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorLivestreamTest.java
index 346872c1e..34b6dc3c1 100644
--- a/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorLivestreamTest.java
+++ b/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorLivestreamTest.java
@@ -8,6 +8,7 @@ import org.schabi.newpipe.extractor.NewPipe;
 import org.schabi.newpipe.extractor.StreamingService;
 import org.schabi.newpipe.extractor.services.DefaultStreamExtractorTest;
 import org.schabi.newpipe.extractor.services.youtube.YoutubeParsingHelper;
+import org.schabi.newpipe.extractor.services.youtube.extractors.YoutubeStreamExtractor;
 import org.schabi.newpipe.extractor.stream.StreamExtractor;
 import org.schabi.newpipe.extractor.stream.StreamType;
 
@@ -30,6 +31,7 @@ public class YoutubeStreamExtractorLivestreamTest extends DefaultStreamExtractor
     public static void setUp() throws Exception {
         YoutubeParsingHelper.resetClientVersionAndKey();
         YoutubeParsingHelper.setNumberGenerator(new Random(1));
+        YoutubeStreamExtractor.resetDeobfuscationCode();
         NewPipe.init(new DownloaderFactory().getDownloader(RESOURCE_PATH + "live"));
         extractor = YouTube.getStreamExtractor(URL);
         extractor.fetchPage();
diff --git a/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorUnlistedTest.java b/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorUnlistedTest.java
index 14a5e755f..29c70da7f 100644
--- a/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorUnlistedTest.java
+++ b/extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorUnlistedTest.java
@@ -6,6 +6,7 @@ import org.schabi.newpipe.extractor.NewPipe;
 import org.schabi.newpipe.extractor.StreamingService;
 import org.schabi.newpipe.extractor.services.DefaultStreamExtractorTest;
 import org.schabi.newpipe.extractor.services.youtube.YoutubeParsingHelper;
+import org.schabi.newpipe.extractor.services.youtube.extractors.YoutubeStreamExtractor;
 import org.schabi.newpipe.extractor.stream.StreamExtractor;
 import org.schabi.newpipe.extractor.stream.StreamType;
 
@@ -28,6 +29,7 @@ public class YoutubeStreamExtractorUnlistedTest extends DefaultStreamExtractorTe
     public static void setUp() throws Exception {
         YoutubeParsingHelper.resetClientVersionAndKey();
         YoutubeParsingHelper.setNumberGenerator(new Random(1));
+        YoutubeStreamExtractor.resetDeobfuscationCode();
         NewPipe.init(new DownloaderFactory().getDownloader(RESOURCE_PATH + "unlisted"));
         extractor = YouTube.getStreamExtractor(URL);
         extractor.fetchPage();