diff --git a/docs/changelog.rst b/docs/changelog.rst
index 8576b85db..8ae854931 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -40,6 +40,8 @@ Detailed list of changes
 
 - Fix a regression in the previous release that caused a :opt:`resize_draw_strategy` of ``static`` to not work (:iss:`5601`)
 
+- Wayland KDE: Fix abort when pasting into Firefox (:iss:`5603`)
+
 0.26.4 [2022-10-17]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/glfw/wl_window.c b/glfw/wl_window.c
index 95eca536a..0f3de081e 100644
--- a/glfw/wl_window.c
+++ b/glfw/wl_window.c
@@ -1691,9 +1691,18 @@ static void primary_selection_source_canceled(void *data UNUSED, struct zwp_prim
     zwp_primary_selection_source_v1_destroy(primary_selection_source);
 }
 
+// KWin aborts if we don't define these even though they are not used for copy/paste
+static void dummy_data_source_target(void* data UNUSED, struct wl_data_source* wl_data_source UNUSED, const char* mime_type UNUSED) {
+}
+
+static void dummy_data_source_action(void* data UNUSED, struct wl_data_source* wl_data_source UNUSED, uint dnd_action UNUSED) {
+}
+
 static const struct wl_data_source_listener data_source_listener = {
     .send = _glfwSendClipboardText,
     .cancelled = data_source_canceled,
+    .target = dummy_data_source_target,
+    .action = dummy_data_source_action,
 };
 
 static const struct zwp_primary_selection_source_v1_listener primary_selection_source_listener = {