diff --git a/CMakeLists.txt b/CMakeLists.txt
index 481294f..d0d6077 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,11 +5,12 @@ project(puzzles
 
 include(cmake/setup.cmake)
 
-add_library(common
+add_library(core_obj OBJECT
   combi.c divvy.c drawing.c dsf.c findloop.c grid.c latin.c
-  laydomino.c loopgen.c malloc.c matching.c midend.c misc.c penrose.c hat.c
-  ps.c random.c sort.c tdq.c tree234.c version.c
-  ${platform_common_sources})
+  laydomino.c loopgen.c malloc.c matching.c midend.c misc.c penrose.c
+  ps.c random.c sort.c tdq.c tree234.c version.c ${platform_common_sources})
+add_library(core $<TARGET_OBJECTS:core_obj>)
+add_library(common $<TARGET_OBJECTS:core_obj> hat.c)
 
 include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 
diff --git a/auxiliary/CMakeLists.txt b/auxiliary/CMakeLists.txt
index f475812..b9c1067 100644
--- a/auxiliary/CMakeLists.txt
+++ b/auxiliary/CMakeLists.txt
@@ -1,6 +1,6 @@
 cliprogram(combi-test combi-test.c)
 cliprogram(divvy-test divvy-test.c)
-cliprogram(hatgen hatgen.c COMPILE_DEFINITIONS TEST_HAT)
+cliprogram(hatgen hatgen.c CORE_LIB COMPILE_DEFINITIONS TEST_HAT)
 cliprogram(hat-test hat-test.c)
 cliprogram(latin-test latin-test.c)
 cliprogram(matching matching.c)
diff --git a/cmake/setup.cmake b/cmake/setup.cmake
index 3c91285..3b73739 100644
--- a/cmake/setup.cmake
+++ b/cmake/setup.cmake
@@ -148,12 +148,18 @@ endfunction()
 # a command-line helper tool.
 function(cliprogram NAME)
   cmake_parse_arguments(OPT
-    "" "" "COMPILE_DEFINITIONS" ${ARGN})
+    "CORE_LIB" "" "COMPILE_DEFINITIONS" ${ARGN})
+
+  if(OPT_CORE_LIB)
+    set(lib core)
+  else()
+    set(lib common)
+  endif()
 
   if(build_cli_programs)
     add_executable(${NAME} ${CMAKE_SOURCE_DIR}/nullfe.c
       ${OPT_UNPARSED_ARGUMENTS})
-    target_link_libraries(${NAME} common ${platform_libs})
+    target_link_libraries(${NAME} ${lib} ${platform_libs})
     if(OPT_COMPILE_DEFINITIONS)
       target_compile_definitions(${NAME} PRIVATE ${OPT_COMPILE_DEFINITIONS})
     endif()