diff --git a/app/src/main/java/com/nextcloud/utils/ical/AndroidCompatTimeZoneRegistry.kt b/app/src/main/java/com/nextcloud/utils/ical/AndroidCompatTimeZoneRegistry.kt
index 7772c3533f0d..c5208b82dab8 100644
--- a/app/src/main/java/com/nextcloud/utils/ical/AndroidCompatTimeZoneRegistry.kt
+++ b/app/src/main/java/com/nextcloud/utils/ical/AndroidCompatTimeZoneRegistry.kt
@@ -47,5 +47,5 @@ class AndroidCompatTimeZoneRegistry : TimeZoneRegistry {
 
     override fun getZoneId(tzId: String): ZoneId = delegate.getZoneId(tzId)
 
-    override fun getTzId(zoneId: String): String = delegate.getTzId(zoneId)
+    override fun getTzId(zoneId: String): String? = delegate.getTzId(zoneId)
 }
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index a42429b6404e..95ca829b2e69 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -38,7 +38,7 @@ firebaseMessagingVersion = "26.0.0"
 fragmentKtxVersion = "1.9.1"
 glide = "5.0.9"
 gsonVersion = "2.14.0"
-ical4jVersion = "4.3.0"
+ical4jVersion = "4.4.0"
 jackrabbitWebdavVersion = "2.13.5"
 jacoco = "0.8.14"
 jsonVersion = "20250517"
diff --git a/gradle/verification-metadata.xml b/gradle/verification-metadata.xml
index 2f47696fd986..642c520b2dd3 100644
--- a/gradle/verification-metadata.xml
+++ b/gradle/verification-metadata.xml
@@ -226,7 +226,10 @@
             <trusting group="org.jspecify" name="jspecify" version="1.0.0"/>
             <trusting group="org.jspecify" name="jspecify" version="1.0.1"/>
          </trusted-key>
-         <trusted-key id="44C9BD32E7CB72F36F49DD0716968D251E760606" group="org.mnode.ical4j" name="ical4j" version="4.3.0"/>
+         <trusted-key id="44C9BD32E7CB72F36F49DD0716968D251E760606">
+            <trusting group="org.mnode.ical4j" name="ical4j" version="4.3.0"/>
+            <trusting group="org.mnode.ical4j" name="ical4j" version="4.4.0"/>
+         </trusted-key>
          <trusted-key id="44F4797A52C336FA666CD9271DE461528F1F1B2A" group="org.apache.jackrabbit"/>
          <trusted-key id="44FBDBBC1A00FE414F1C1873586654072EAD6677" group="org.sonatype.oss" name="oss-parent" version="9"/>
          <trusted-key id="453EA31328DE7D8AAA55AD4ED56C721C1CFF1424" group="^com[.]twelvemonkeys($|([.].*))" regex="true"/>