diff --git a/src/SPC/builder/unix/library/libjxl.php b/src/SPC/builder/unix/library/libjxl.php
index 13f8481b..4c922d9d 100644
--- a/src/SPC/builder/unix/library/libjxl.php
+++ b/src/SPC/builder/unix/library/libjxl.php
@@ -29,13 +29,17 @@ trait libjxl
             );
 
         if (ToolchainManager::getToolchainClass() === ZigToolchain::class) {
-            $cmake->addConfigureArgs(
-                '-DCXX_MAVX512F_SUPPORTED:BOOL=FALSE',
-                '-DCXX_MAVX512DQ_SUPPORTED:BOOL=FALSE',
-                '-DCXX_MAVX512CD_SUPPORTED:BOOL=FALSE',
-                '-DCXX_MAVX512BW_SUPPORTED:BOOL=FALSE',
-                '-DCXX_MAVX512VL_SUPPORTED:BOOL=FALSE'
-            );
+            $cflags = getenv('SPC_DEFAULT_C_FLAGS') ?: getenv('CFLAGS') ?: '';
+            $has_avx512 = str_contains($cflags, '-mavx512') || str_contains($cflags, '-march=x86-64-v4');
+            if (!$has_avx512) {
+                $cmake->addConfigureArgs(
+                    '-DCXX_MAVX512F_SUPPORTED:BOOL=FALSE',
+                    '-DCXX_MAVX512DQ_SUPPORTED:BOOL=FALSE',
+                    '-DCXX_MAVX512CD_SUPPORTED:BOOL=FALSE',
+                    '-DCXX_MAVX512BW_SUPPORTED:BOOL=FALSE',
+                    '-DCXX_MAVX512VL_SUPPORTED:BOOL=FALSE'
+                );
+            }
         }
 
         $cmake->build();
diff --git a/src/SPC/builder/unix/library/libwebp.php b/src/SPC/builder/unix/library/libwebp.php
index 46a88af4..788d069f 100644
--- a/src/SPC/builder/unix/library/libwebp.php
+++ b/src/SPC/builder/unix/library/libwebp.php
@@ -10,8 +10,13 @@ trait libwebp
 {
     protected function build(): void
     {
+        $cflags = getenv('SPC_DEFAULT_C_FLAGS') ?: getenv('CFLAGS') ?: '';
+        $has_avx2 = str_contains($cflags, '-mavx2') || str_contains($cflags, '-march=x86-64-v2') || str_contains($cflags, '-march=x86-64-v3');
         UnixCMakeExecutor::create($this)
-            ->addConfigureArgs('-DWEBP_BUILD_EXTRAS=ON')
+            ->addConfigureArgs(
+                '-DWEBP_BUILD_EXTRAS=ON',
+                '-DWEBP_ENABLE_SIMD=' . ($has_avx2 ? 'ON' : 'OFF'),
+            )
             ->build();
         // patch pkgconfig
         $this->patchPkgconfPrefix(patch_option: PKGCONF_PATCH_PREFIX | PKGCONF_PATCH_LIBDIR);