diff --git a/CHANGES b/CHANGES
index 17e8e4a0ad..b3d6ee3cb0 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,10 @@
+8.0.0-dev.435 | 2025-06-17 09:25:30 +0200
+
+  * GH-4573: IOSource: Remove IsPacketSource (Arne Welzel, Corelight)
+
+    This wasn't used in tree and even the PktSrc class doesn't override this
+    to return true, so just remove it outright without deprecation.
+
 8.0.0-dev.433 | 2025-06-16 14:58:12 +0200
 
   * btest/logging: Fly-by cleanup (Arne Welzel, Corelight)
diff --git a/NEWS b/NEWS
index a760d948cd..a28285dae8 100644
--- a/NEWS
+++ b/NEWS
@@ -48,6 +48,9 @@ Breaking Changes
 
 	redef EventMetadata::add_missing_remote_network_timestamp = T;
 
+- The ``IsPacketSource()`` method on ``IOSource`` was removed. It was unused
+  and incorrectly returned ``false`` on all packet sources.
+
 New Functionality
 -----------------
 
diff --git a/VERSION b/VERSION
index 9e09e6382d..f720a2d61b 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-8.0.0-dev.433
+8.0.0-dev.435
diff --git a/src/iosource/IOSource.h b/src/iosource/IOSource.h
index 599b4a4c7e..60f2abd896 100644
--- a/src/iosource/IOSource.h
+++ b/src/iosource/IOSource.h
@@ -32,11 +32,6 @@ public:
      */
     bool IsOpen() const { return ! closed; }
 
-    /**
-     * Returns true if this is a packet source.
-     */
-    virtual bool IsPacketSource() const { return false; }
-
     /**
      * Initializes the source. Can be overwritten by derived classes.
      */