diff --git a/ASAN.md b/ASAN.md
new file mode 100644
index 000000000..e38a61e8e
--- /dev/null
+++ b/ASAN.md
@@ -0,0 +1,61 @@
+# Address Sanitizer (ASAN) Guide
+
+This project supports Address Sanitizer (ASAN) to help detect memory corruption,
+use-after-free, and buffer overflows in the C/C++ NetHack engine and its Python
+extensions.
+
+## Enabling ASAN
+
+ASAN is integrated into the CMake build system and can be enabled by editing
+`pyproject.toml`.
+
+### Current Configuration
+
+```toml
+[tool.scikit-build]
+cmake.build-type = "Release"
+cmake.args = ["-DHACKDIR=nle/nethackdir", "-DPYTHON_PACKAGE_NAME=nle"]
+```
+
+To enable ASAN, add the cmake argument `-DENABLE_ASAN=On` and switch
+`cmake.build-type` to `Debug`.
+
+## Running Tests with ASAN
+
+Because the Python interpreter itself is not built with ASAN, you must preload
+the ASAN runtime library when running tests.
+
+```bash
+LD_PRELOAD=$(gcc -print-file-name=libasan.so):$(gcc -print-file-name=libstdc++.so) \
+ASAN_OPTIONS=detect_leaks=0 \
+uv run pytest
+```
+
+_Note: Preloading `libstdc++.so` may be necessary on some platforms (like
+aarch64 Linux) to avoid crashes when C++ exceptions are thrown._
+
+### Why `detect_leaks=0`?
+
+We disable the LeakSanitizer (`detect_leaks=0`) for several reasons:
+
+1. Python Shutdown: CPython does not free all memory at exit (e.g., global
+   singletons, interned strings). This is intentional for performance but is
+   flagged as a "leak" by ASAN.
+2. Pytest State: `pytest` keeps tracebacks, local variables, and fixture data in
+   memory until the end of the session to generate reports.
+3. Standard Interpreter: Since we are running a sanitized C extension inside a
+   non-sanitized Python interpreter, the leak detector cannot accurately track
+   the ownership boundary between the two.
+
+Disabling leak detection still allows ASAN to catch critical memory corruption
+errors (Buffer Overflows, Use-After-Free, etc.) as they happen.
+
+## Other Sanitizers
+
+The build system also supports:
+
+- Thread Sanitizer (TSAN): Use `-DENABLE_TSAN=ON`.
+- Undefined Behavior Sanitizer (UBSAN): Use `-DENABLE_UBSAN=ON`.
+
+To use these, update `pyproject.toml` accordingly and preload the corresponding
+library (e.g., `libtsan.so`).
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 48a45e4b8..dbcfebead 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,24 +16,51 @@ if(CMAKE_BUILD_TYPE MATCHES Debug)
   message("Debug build.")
   # Unclear if this is even necessary. `dsymutil rlmain -o rlmain.dSYM` seems to
   # have done the trick.
-  set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -g")
   set(CMAKE_XCODE_ATTRIBUTE_DEBUG_INFORMATION_FORMAT "dwarf-with-dsym")
 
-  if(0)
-    # address sanitizer.
-    set(CMAKE_CXX_FLAGS_DEBUG
-        "${CMAKE_CXX_FLAGS_DEBUG} -fno-omit-frame-pointer -fsanitize=address")
-    set(CMAKE_C_FLAGS_DEBUG
-        "${CMAKE_C_FLAGS_DEBUG} -fno-omit-frame-pointer -fsanitize=address")
-    set(CMAKE_LINKER_FLAGS_DEBUG
-        "${CMAKE_LINKER_FLAGS_DEBUG} -fno-omit-frame-pointer -fsanitize=address"
-    )
-  endif()
-  if(MSVC)
-    add_compile_options(/W4)
-  else()
-    add_compile_options(-Wall)
+  option(ENABLE_ASAN "Enable Address Sanitizer" OFF)
+  option(ENABLE_TSAN "Enable Thread Sanitizer" OFF)
+  option(ENABLE_UBSAN "Enable Undefined Behavior Sanitizer" OFF)
+
+  if(ENABLE_ASAN
+     OR ENABLE_TSAN
+     OR ENABLE_UBSAN)
+    include(CheckCXXCompilerFlag)
+    include(CheckCCompilerFlag)
+    add_library(nle_sanitizers INTERFACE)
+
+    if(ENABLE_ASAN)
+      set(SANITIZER_FLAGS_ASAN -fsanitize=address -fno-omit-frame-pointer)
+      check_cxx_compiler_flag("${SANITIZER_FLAGS_ASAN}" COMPILER_SUPPORTS_ASAN)
+      if(COMPILER_SUPPORTS_ASAN)
+        target_compile_options(nle_sanitizers INTERFACE ${SANITIZER_FLAGS_ASAN})
+        target_link_options(nle_sanitizers INTERFACE ${SANITIZER_FLAGS_ASAN})
+      endif()
+    endif()
+
+    if(ENABLE_TSAN)
+      set(SANITIZER_FLAGS_TSAN "-fsanitize=thread -fno-omit-frame-pointer")
+      check_cxx_compiler_flag("${SANITIZER_FLAGS_TSAN}" COMPILER_SUPPORTS_TSAN)
+      if(COMPILER_SUPPORTS_TSAN)
+        target_compile_options(nle_sanitizers INTERFACE ${SANITIZER_FLAGS_TSAN})
+        target_link_options(nle_sanitizers INTERFACE ${SANITIZER_FLAGS_TSAN})
+      endif()
+    endif()
+
+    if(ENABLE_UBSAN)
+      set(SANITIZER_FLAGS_UBSAN "-fsanitize=undefined -fno-omit-frame-pointer")
+      check_cxx_compiler_flag("${SANITIZER_FLAGS_UBSAN}"
+                              COMPILER_SUPPORTS_UBSAN)
+      if(COMPILER_SUPPORTS_UBSAN)
+        target_compile_options(nle_sanitizers
+                               INTERFACE ${SANITIZER_FLAGS_UBSAN})
+        target_link_options(nle_sanitizers INTERFACE ${SANITIZER_FLAGS_UBSAN})
+      endif()
+    endif()
+
+    link_libraries(nle_sanitizers)
   endif()
+
 elseif(CMAKE_BUILD_TYPE MATCHES Release)
   message("Release build.")
 else()
@@ -42,11 +69,6 @@ endif()
 
 message(STATUS "Building nle backend version: ${CMAKE_NLE_VERSION}")
 
-set(CMAKE_POSITION_INDEPENDENT_CODE ON)
-
-add_compile_options(-Wno-deprecated-non-prototype)
-add_compile_options(-Wno-unused-variable)
-
 set(HACKDIR
     "$ENV{HOME}/nethackdir.nle"
     CACHE STRING "Configuration files for nethack")
@@ -57,6 +79,29 @@ message(STATUS "HACKDIR set to: ${HACKDIR}")
 set(VARDIR ${HACKDIR})
 set(INSTDIR ${HACKDIR})
 
+add_library(nle_common_options INTERFACE)
+set_target_properties(nle_common_options
+                      PROPERTIES INTERFACE_POSITION_INDEPENDENT_CODE ON)
+
+target_compile_definitions(
+  nle_common_options
+  INTERFACE GCC_WARN
+            NOCLIPPING
+            NOMAIL
+            NOTPARMDECL
+            HACKDIR="${HACKDIR}"
+            DEFAULT_WINDOW_SYS="rl"
+            DLB
+            NOCWD_ASSUMPTIONS
+            NLE_USE_TILES
+            NOCWD_ASSUMPTIONS)
+
+if(MSVC)
+  target_compile_options(nle_common_options INTERFACE /W4)
+else()
+  target_compile_options(nle_common_options INTERFACE -Wall)
+endif()
+
 # pybind11 via FetchContent
 include(FetchContent)
 FetchContent_Declare(
@@ -73,16 +118,6 @@ FetchContent_Declare(
   GIT_HASH "259fc4103bad6bb484d5ff426ace56ac557107a4" EXCLUDE_FROM_ALL)
 FetchContent_MakeAvailable(deboost_context)
 
-add_compile_definitions(
-  GCC_WARN
-  NOCLIPPING
-  NOMAIL
-  NOTPARMDECL
-  HACKDIR="${HACKDIR}"
-  DEFAULT_WINDOW_SYS="rl"
-  DLB
-  NOCWD_ASSUMPTIONS)
-
 set(NLE_SRC ${nle_SOURCE_DIR}/src)
 set(NLE_INC ${nle_SOURCE_DIR}/include)
 set(NLE_DAT ${nle_SOURCE_DIR}/dat)
@@ -155,19 +190,20 @@ target_include_directories(
 # Careful with -DMONITOR_HEAP: Ironically, it fails to fclose FILE* heaplog.
 # target_compile_definitions(nethack PUBLIC "$<$<CONFIG:DEBUG>:MONITOR_HEAP>")
 
-target_link_libraries(nethack PUBLIC m fcontext bz2_static tmt)
+target_link_libraries(nethack PUBLIC nle_common_options m fcontext bz2_static
+                                     tmt)
 
 # dlopen wrapper library
 add_library(nethackdl STATIC "sys/unix/nledl.c")
 target_include_directories(
   nethackdl PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/include
                    ${deboost_context_SOURCE_DIR}/include)
-target_link_libraries(nethackdl PUBLIC dl)
+target_link_libraries(nethackdl PUBLIC nle_common_options dl)
 
 # rlmain C++ (test) binary
 add_executable(rlmain "sys/unix/rlmain.cc")
 set_target_properties(rlmain PROPERTIES CXX_STANDARD 11)
-target_link_libraries(rlmain PUBLIC nethackdl)
+target_link_libraries(rlmain PUBLIC nle_common_options nethackdl)
 target_include_directories(rlmain PUBLIC ${NLE_INC_GEN})
 add_dependencies(rlmain util) # For pm.h.
 
@@ -180,7 +216,7 @@ pybind11_add_module(
   src/drawing.c
   src/objects.c
   $<TARGET_OBJECTS:tile>)
-target_link_libraries(_pynethack PUBLIC nethackdl)
+target_link_libraries(_pynethack PUBLIC nle_common_options nethackdl)
 set_target_properties(_pynethack PROPERTIES CXX_STANDARD 14)
 target_include_directories(_pynethack PUBLIC ${NLE_INC_GEN} ${NLE_WIN}/share)
 # add_dependencies(_pynethack util tile) # For pm.h.
@@ -193,19 +229,19 @@ target_include_directories(
   converter
   PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/third_party/libtmt
          ${CMAKE_CURRENT_SOURCE_DIR}/third_party/converter ${bzip2_SOURCE_DIR})
-target_link_libraries(converter PUBLIC bz2_static tmt)
+target_link_libraries(converter PUBLIC nle_common_options bz2_static tmt)
 if(CMAKE_BUILD_TYPE MATCHES Debug)
   target_compile_options(converter PRIVATE -Wall -Wextra -pedantic -Werror)
 endif()
 
 # ttyrec reader executable
 add_executable(ttyrec_reader EXCLUDE_FROM_ALL "third_party/converter/reader.c")
-target_link_libraries(ttyrec_reader PUBLIC converter)
+target_link_libraries(ttyrec_reader PUBLIC nle_common_options converter)
 target_include_directories(
   ttyrec_reader PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/third_party/converter)
 
 pybind11_add_module(_pyconverter third_party/converter/pyconverter.cc)
-target_link_libraries(_pyconverter PUBLIC converter)
+target_link_libraries(_pyconverter PUBLIC nle_common_options converter)
 set_target_properties(_pyconverter PROPERTIES CXX_STANDARD 14)
 target_include_directories(
   _pyconverter PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/third_party/converter)
diff --git a/nle/tests/test_system.py b/nle/tests/test_system.py
index 9fe5e60be..9cc1de4f4 100644
--- a/nle/tests/test_system.py
+++ b/nle/tests/test_system.py
@@ -1,4 +1,7 @@
 # Copyright (c) Facebook, Inc. and its affiliates.
+
+import ctypes
+import functools
 import multiprocessing as mp
 import queue
 import random
@@ -19,17 +22,32 @@ def new_env_one_step():
     return terminated
 
 
+@functools.cache
+def is_asan():
+    """Checks if the process is running with ASAN.
+
+    See if the __asan_init symbol is present in the current process.
+    """
+
+    current_process = ctypes.CDLL(None)
+    return hasattr(current_process, "__asan_init")
+
+
 @pytest.mark.parametrize(
     "ctx", [mp.get_context(m) for m in START_METHODS], ids=START_METHODS
 )
 class TestEnvSubprocess:
     def test_env_in_subprocess(self, ctx):
+        if ctx.get_start_method() == "spawn" and is_asan():
+            pytest.skip("ASAN crashes on spawn on this environment")
         p = ctx.Process(target=new_env_one_step)
         p.start()
         p.join()
         assert p.exitcode == 0
 
     def test_env_before_and_in_subprocess(self, ctx):
+        if ctx.get_start_method() == "spawn" and is_asan():
+            pytest.skip("ASAN crashes on spawn on this environment")
         new_env_one_step()
         p = ctx.Process(target=new_env_one_step)
         p.start()
diff --git a/util/CMakeLists.txt b/util/CMakeLists.txt
index 4f0194b67..a796ddb5d 100644
--- a/util/CMakeLists.txt
+++ b/util/CMakeLists.txt
@@ -27,18 +27,27 @@ file(MAKE_DIRECTORY ${NLE_INC_GEN} ${NLE_SRC_GEN})
 add_executable(makedefs ${MAKEDEFS_SRC})
 target_include_directories(makedefs PRIVATE ${NLE_INC} ${NLE_INC_GEN}
                                             ${NLE_UTIL_GEN})
+target_link_libraries(makedefs PRIVATE nle_common_options)
+
 add_executable(dgn_comp ${DGN_COMP_SRC})
 target_include_directories(dgn_comp PRIVATE ${NLE_INC} ${NLE_INC_GEN}
                                             ${NLE_UTIL_GEN})
+target_link_libraries(dgn_comp PRIVATE nle_common_options)
+
 add_executable(lev_comp ${LEV_COMP_SRC})
 target_include_directories(lev_comp PRIVATE ${NLE_INC} ${NLE_INC_GEN}
                                             ${NLE_UTIL_GEN})
+target_link_libraries(lev_comp PRIVATE nle_common_options)
+
 add_executable(dlb ${DLB_SRC})
 target_include_directories(dlb PRIVATE ${NLE_INC} ${NLE_INC_GEN}
                                        ${NLE_UTIL_GEN})
+target_link_libraries(dlb PRIVATE nle_common_options)
+
 add_executable(recover recover.c)
 target_include_directories(recover PRIVATE ${NLE_INC} ${NLE_INC_GEN}
                                            ${NLE_UTIL_GEN})
+target_link_libraries(recover PRIVATE nle_common_options)
 
 add_custom_command(
   DEPENDS makedefs
@@ -90,6 +99,7 @@ add_custom_target(util DEPENDS ${MAKEDEFS_HEADERS} recover)
 
 add_executable(tilemap ${NLE_WIN}/share/tilemap.c)
 target_include_directories(tilemap PUBLIC ${NLE_INC} ${NLE_INC_GEN})
+target_link_libraries(tilemap PRIVATE nle_common_options)
 add_dependencies(tilemap util)
 
 file(GLOB NETHACK_TILE_SRC ${NLE_WIN}/rl/tile2rgb.c ${NLE_WIN}/rl/nletiletxt.c
@@ -97,7 +107,7 @@ file(GLOB NETHACK_TILE_SRC ${NLE_WIN}/rl/tile2rgb.c ${NLE_WIN}/rl/nletiletxt.c
 add_library(tile OBJECT ${NETHACK_TILE_SRC} ${NLE_SRC_GEN}/tile.c)
 target_include_directories(tile PUBLIC ${NLE_INC} ${NLE_INC_GEN}
                                        ${NLE_WIN}/share)
-add_dependencies(tile generate_pm_h generate_tile_c)
+add_dependencies(tile generate_pm_h generate_tile_c nle_common_options)
 
 # NOTE: util is dependent on these two
 add_dependencies(lev_comp util)