diff --git a/NEWS b/NEWS
index ccf6a16bc5..530a723005 100644
--- a/NEWS
+++ b/NEWS
@@ -22,6 +22,10 @@ Breaking Changes
   ZEEK_SPICY_MODULE_PATH are now skipped. Dot directories explicitly listed in
   ZEEK_PLUGIN_PATH or ZEEK_SPICY_MODULE_PATH are not skipped.
 
+- External plugins are now required to raise their minimum required CMake version
+  to 3.15. This was previously warned about, but has caused user confusion in
+  errors cases around the IN_LIST operator.
+
 New Functionality
 -----------------
 
diff --git a/cmake b/cmake
index 164243f93e..cc923365ea 160000
--- a/cmake
+++ b/cmake
@@ -1 +1 @@
-Subproject commit 164243f93eea1a20cb4b918e7f168ff89ca71d62
+Subproject commit cc923365ead6b827354e70d4a03d531fe3f5e9d3
diff --git a/testing/builtin-plugins/Files/protocol-plugin/CMakeLists.txt b/testing/builtin-plugins/Files/protocol-plugin/CMakeLists.txt
index c7e685cd1e..d696055380 100644
--- a/testing/builtin-plugins/Files/protocol-plugin/CMakeLists.txt
+++ b/testing/builtin-plugins/Files/protocol-plugin/CMakeLists.txt
@@ -1,6 +1,6 @@
 project(Zeek-Plugin-Demo-Foo)
 
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.15 FATAL_ERROR)
 
 if (NOT ZEEK_DIST)
     message(FATAL_ERROR "ZEEK_DIST not set")
diff --git a/testing/builtin-plugins/Files/py-lib-plugin/CMakeLists.txt b/testing/builtin-plugins/Files/py-lib-plugin/CMakeLists.txt
index 76936614fa..6a151b7dc9 100644
--- a/testing/builtin-plugins/Files/py-lib-plugin/CMakeLists.txt
+++ b/testing/builtin-plugins/Files/py-lib-plugin/CMakeLists.txt
@@ -1,4 +1,6 @@
-cmake_minimum_required(VERSION 3.5 FATAL_ERROR)
+project(Zeek-Plugin-Demo-Python)
+
+cmake_minimum_required(VERSION 3.15 FATAL_ERROR)
 
 find_package(PythonLibs REQUIRED)
 
diff --git a/testing/builtin-plugins/Files/zeek-version-plugin/CMakeLists.txt b/testing/builtin-plugins/Files/zeek-version-plugin/CMakeLists.txt
index 431677ab2b..1e53050f5c 100644
--- a/testing/builtin-plugins/Files/zeek-version-plugin/CMakeLists.txt
+++ b/testing/builtin-plugins/Files/zeek-version-plugin/CMakeLists.txt
@@ -1,6 +1,6 @@
 project(Zeek-Plugin-Demo-Version)
 
-cmake_minimum_required(VERSION 3.15)
+cmake_minimum_required(VERSION 3.15 FATAL_ERROR)
 
 if (NOT ZEEK_DIST)
     message(FATAL_ERROR "ZEEK_DIST not set")