diff --git a/src/js/biditrie.js b/src/js/biditrie.js
index 2fa049506..560d5918a 100644
--- a/src/js/biditrie.js
+++ b/src/js/biditrie.js
@@ -582,7 +582,7 @@ class BidiTrieContainer {
     }
 
     toSelfie() {
-        const buf32 = this.buf32.slice(0, this.buf32[CHAR1_SLOT] + 3 >>> 2);
+        const buf32 = this.buf32.subarray(0, this.buf32[CHAR1_SLOT] + 3 >>> 2);
         return { buf32, checksum: i32Checksum(buf32) };
     }
 
diff --git a/src/js/hntrie.js b/src/js/hntrie.js
index 5885e6e21..518d0b8dd 100644
--- a/src/js/hntrie.js
+++ b/src/js/hntrie.js
@@ -452,7 +452,7 @@ class HNTrieContainer {
     }
 
     toSelfie() {
-        const buf32 = this.buf32.slice(0, this.buf32[CHAR1_SLOT] + 3 >>> 2);
+        const buf32 = this.buf32.subarray(0, this.buf32[CHAR1_SLOT] + 3 >>> 2);
         return { buf32, checksum: i32Checksum(buf32) };
     }
 
diff --git a/src/js/static-net-filtering.js b/src/js/static-net-filtering.js
index ac4b373df..ec62bb945 100644
--- a/src/js/static-net-filtering.js
+++ b/src/js/static-net-filtering.js
@@ -495,7 +495,7 @@ const filterDataReset = ( ) => {
     filterDataWritePtr = 2;
 };
 const filterDataToSelfie = ( ) =>
-    filterData.slice(0, filterDataWritePtr);
+    filterData.subarray(0, filterDataWritePtr);
 
 const filterDataFromSelfie = selfie => {
     if ( selfie instanceof Int32Array === false ) { return false; }
@@ -3193,7 +3193,7 @@ const urlTokenizer = new (class {
     }
 
     toSelfie() {
-        return this.knownTokens.slice();
+        return this.knownTokens;
     }
 
     fromSelfie(selfie) {
@@ -4779,7 +4779,7 @@ StaticNetFilteringEngine.prototype.toSelfie = function() {
         processedFilterCount: this.processedFilterCount,
         acceptedCount: this.acceptedCount,
         discardedCount: this.discardedCount,
-        bitsToBucket: new Map(this.bitsToBucket),
+        bitsToBucket: this.bitsToBucket,
         urlTokenizer: urlTokenizer.toSelfie(),
         destHNTrieContainer: destHNTrieContainer.toSelfie(),
         origHNTrieContainer: origHNTrieContainer.toSelfie(),