diff --git a/CMakeLists.txt b/CMakeLists.txt
index f770602..1404764 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,7 +10,7 @@ set(libucore_VERSION ${libucore_VERSION_MAJOR}.${libucore_VERSION_MINOR}.${libuc
 
 set(CMAKE_VERBOSE_MAKEFILE ON)
 
-set(CMAKE_C_STANDARD 11)
+set(CMAKE_C_STANDARD 17)
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Wundef -Wcast-qual -Wshadow -Wcast-align -pipe -Wno-unused-parameter -Werror=implicit-function-declaration -Winit-self")
 add_definitions(-D_FILE_OFFSET_BITS=64)
 set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -O2")
@@ -30,13 +30,14 @@ if (CODE_COVERAGE)
   set(build_type "${build_type}-coverage")
 endif()
 
+add_compile_definitions($<$<CONFIG:Debug>:DEBUG>)
 option(BUILD_SANITIZE "build with address sanitizer" OFF)
 if (BUILD_SANITIZE)
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=address")
   set(build_type "${build_type}-sanitize")
 endif()
-
-
+find_package(PkgConfig REQUIRED)
+pkg_check_modules(CHECK REQUIRED IMPORTED_TARGET check)
 include_directories(include)
 
 add_subdirectory(src)
diff --git a/include/ucore/sarena.h b/include/ucore/sarena.h
index ed4f09a..afffc96 100644
--- a/include/ucore/sarena.h
+++ b/include/ucore/sarena.h
@@ -25,9 +25,9 @@ extern "C" {
 */
 typedef struct UCSArena UCSArena;
 struct UCSArena {
-    char *start; // start of user buffer
-    char *curr;  // next alloc point
-    char *end;   // one past end of user buffer
+    unsigned char *start; // start of user buffer
+    unsigned char *curr;  // next alloc point
+    unsigned char *end;   // one past end of user buffer
 };
 
 /** Initialize a UCSArena with predefined backing array.
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 6e9f79b..e771441 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -1,6 +1,6 @@
 file(GLOB TEST_SOURCE_FILES test_*.c)
 
-link_libraries(check ucore Threads::Threads)
+link_libraries(ucore Threads::Threads PkgConfig::CHECK)
 if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
     include_directories("/opt/homebrew/include")
     link_directories("/opt/homebrew/lib")