diff --git a/src/cluster/backend/CMakeLists.txt b/src/cluster/backend/CMakeLists.txt
index 0e5d704186..109bdc411f 100644
--- a/src/cluster/backend/CMakeLists.txt
+++ b/src/cluster/backend/CMakeLists.txt
@@ -1,4 +1,17 @@
-option(ENABLE_CLUSTER_BACKEND_ZEROMQ "Enable the ZeroMQ cluster backend" ON)
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/zeromq/cmake")
+
+find_package(ZeroMQ)
+
+# Default to building ZeroMQ only if ZeroMQ was found.
+#
+# If a user enabled the cluster backend explicitly (-D ENABLE_CLUSTER_BACKEND_ZEROMQ:bool=ON),
+# but ZeroMQ wasn' found, hard bail.
+option(ENABLE_CLUSTER_BACKEND_ZEROMQ "Enable the ZeroMQ cluster backend" ${ZeroMQ_FOUND})
+
 if (ENABLE_CLUSTER_BACKEND_ZEROMQ)
+    if (NOT ZeroMQ_FOUND)
+        message(FATAL_ERROR "ENABLE_CLUSTER_BACKEND_ZEROMQ set, but ZeroMQ library not available")
+    endif ()
+
     add_subdirectory(zeromq)
 endif ()
diff --git a/src/cluster/backend/zeromq/CMakeLists.txt b/src/cluster/backend/zeromq/CMakeLists.txt
index a15923445a..9895f4faf2 100644
--- a/src/cluster/backend/zeromq/CMakeLists.txt
+++ b/src/cluster/backend/zeromq/CMakeLists.txt
@@ -2,8 +2,6 @@ list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 
 find_package(ZeroMQ REQUIRED)
 
-message(STATUS "zeromq: ${ZeroMQ_LIBRARIES} ${ZeroMQ_INCLUDE_DIRS}")
-
 zeek_add_plugin(
     Zeek
     Cluster_Backend_ZeroMQ
diff --git a/src/cluster/backend/zeromq/cmake/FindZeroMQ.cmake b/src/cluster/backend/zeromq/cmake/FindZeroMQ.cmake
index 964f6a457d..92d1e94890 100644
--- a/src/cluster/backend/zeromq/cmake/FindZeroMQ.cmake
+++ b/src/cluster/backend/zeromq/cmake/FindZeroMQ.cmake
@@ -1,5 +1,7 @@
 include(FindPackageHandleStandardArgs)
 
+set(AUXIL_CPPZMQ_DIR ${CMAKE_CURRENT_LIST_DIR}/../auxil/cppzmq)
+
 find_library(ZeroMQ_LIBRARY NAMES zmq HINTS ${ZeroMQ_ROOT_DIR}/lib)
 
 find_path(ZeroMQ_INCLUDE_DIR NAMES zmq.h HINTS ${ZeroMQ_ROOT_DIR}/include)
@@ -31,18 +33,14 @@ endif ()
 
 if (NOT ZeroMQ_CPP_VERSION)
     # Probably no zmq.hpp file, use the version from auxil
-    set(ZeroMQ_CPP_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/auxil/cppzmq"
-        CACHE FILEPATH "Include path for cppzmq" FORCE)
+    set(ZeroMQ_CPP_INCLUDE_DIR ${AUXIL_CPPZMQ_DIR} CACHE FILEPATH "Include path for cppzmq" FORCE)
     set_cppzmq_version()
 elseif (ZeroMQ_CPP_VERSION VERSION_LESS "4.9.0")
     message(STATUS "Found old cppzmq version ${ZeroMQ_CPP_VERSION}, using bundled version")
-    set(ZeroMQ_CPP_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/auxil/cppzmq"
-        CACHE FILEPATH "Include path for cppzmq" FORCE)
+    set(ZeroMQ_CPP_INCLUDE_DIR ${AUXIL_CPPZMQ_DIR} CACHE FILEPATH "Include path for cppzmq" FORCE)
     set_cppzmq_version()
 endif ()
 
-message(STATUS "Using cppzmq ${ZeroMQ_CPP_VERSION} from ${ZeroMQ_CPP_INCLUDE_DIR}")
-
 find_package_handle_standard_args(
     ZeroMQ FOUND_VAR ZeroMQ_FOUND REQUIRED_VARS ZeroMQ_LIBRARY ZeroMQ_INCLUDE_DIR
                                                 ZeroMQ_CPP_INCLUDE_DIR ZeroMQ_CPP_VERSION)