diff --git a/nc_cxx.cmake b/nc_cxx.cmake
index 1cf0b58..40b5667 100644
--- a/nc_cxx.cmake
+++ b/nc_cxx.cmake
@@ -89,6 +89,10 @@ append_compile_flag("-fvisibility=hidden")
 append_compile_flag("-fvisibility-inlines-hidden")
 append_compile_flag("-fPIC")
 
+# Clang doesn't enabled sized deallocation (__cpp_sized_deallocation) by
+# default, at least by clang-15, so we have to enable it explicitly.
+append_compile_flag("-fsized-deallocation")
+
 # We want a build-id so that we can attribute minidumps
 append_link_flag("-Wl,--build-id")
 
diff --git a/nc_warnings.cmake b/nc_warnings.cmake
index 53849ea..442e920 100644
--- a/nc_warnings.cmake
+++ b/nc_warnings.cmake
@@ -53,6 +53,9 @@ append_compile_flag(-Wswitch)
 # with language primitives like range-for.
 # append_compile_flag(-Wunsafe-loop-optimizations)
 
+# gcc warnings with unknown version
+append_compile_flag(-Wsized-deallocation)
+
 # gcc-6.1.0 warnings
 append_compile_flag(-Wshift-negative-value)
 append_compile_flag(-Wnull-dereference)
@@ -101,7 +104,6 @@ append_compile_flag(-Wbitwise-instead-of-logical)
 append_compile_flag(-Wunaligned-access)
 append_compile_flag(-Wunreachable-code-fallthrough)
 
-
 # -------------------------------------------------------------------------
 # Required extensions
 #AX_APPEND_COMPILE_FLAGS([-Wgnu-flexible-array-union-member], [], [-Werror])