diff --git a/config/lib.json b/config/lib.json
index c326c6cf..6bf3e03f 100644
--- a/config/lib.json
+++ b/config/lib.json
@@ -470,11 +470,6 @@
         "static-libs-unix": [
             "libiconv.a",
             "libcharset.a"
-        ],
-        "headers": [
-            "iconv.h",
-            "libcharset.h",
-            "localcharset.h"
         ]
     },
     "libiconv-win": {
@@ -1011,32 +1006,21 @@
     },
     "zlib": {
         "source": "zlib",
-        "static-libs-unix": [
-            "libz.a"
+        "pkg-configs": [
+            "zlib"
         ],
         "static-libs-windows": [
             "zlib_a.lib"
-        ],
-        "headers": [
-            "zlib.h",
-            "zconf.h"
         ]
     },
     "zstd": {
         "source": "zstd",
-        "static-libs-unix": [
-            "libzstd.a"
+        "pkg-configs": [
+            "libzstd"
         ],
         "static-libs-windows": [
-            [
-                "zstd.lib",
-                "zstd_static.lib"
-            ]
-        ],
-        "headers-unix": [
-            "zdict.h",
-            "zstd.h",
-            "zstd_errors.h"
+            "zstd.lib",
+            "zstd_static.lib"
         ],
         "headers-windows": [
             "zstd.h",
diff --git a/src/SPC/builder/LibraryBase.php b/src/SPC/builder/LibraryBase.php
index 383faa41..701aeedb 100644
--- a/src/SPC/builder/LibraryBase.php
+++ b/src/SPC/builder/LibraryBase.php
@@ -376,7 +376,7 @@ abstract class LibraryBase
             }
         }
         $pkg_config_path = getenv('PKG_CONFIG_PATH') ?: '';
-        $search_paths = array_filter(explode(is_unix() ? ':' : ';', $pkg_config_path));
+        $search_paths = array_unique(array_filter(explode(is_unix() ? ':' : ';', $pkg_config_path)));
         foreach (Config::getLib(static::NAME, 'pkg-configs', []) as $name) {
             $found = false;
             foreach ($search_paths as $path) {
diff --git a/src/SPC/builder/unix/library/zlib.php b/src/SPC/builder/unix/library/zlib.php
index 394e4a4f..aa3f38e2 100644
--- a/src/SPC/builder/unix/library/zlib.php
+++ b/src/SPC/builder/unix/library/zlib.php
@@ -10,7 +10,8 @@ trait zlib
 {
     protected function build(): void
     {
-        UnixAutoconfExecutor::create($this)->exec("./configure --static --prefix={$this->getBuildRootPath()}")->make();
+        $static = getenv('SPC_STATIC_LIBS') ? '--static' : '';
+        UnixAutoconfExecutor::create($this)->exec("./configure {$static} --prefix={$this->getBuildRootPath()}")->make();
         $this->patchPkgconfPrefix(['zlib.pc']);
     }
 }
diff --git a/src/SPC/builder/unix/library/zstd.php b/src/SPC/builder/unix/library/zstd.php
index 59b26701..ca05bf0c 100644
--- a/src/SPC/builder/unix/library/zstd.php
+++ b/src/SPC/builder/unix/library/zstd.php
@@ -13,10 +13,10 @@ trait zstd
         UnixCMakeExecutor::create($this)
             ->setBuildDir("{$this->source_dir}/build/cmake/build")
             ->addConfigureArgs(
-                '-DZSTD_BUILD_STATIC=ON',
-                '-DZSTD_BUILD_SHARED=OFF',
+                '-DZSTD_BUILD_STATIC=' . (getenv('SPC_STATIC_LIBS') ? 'ON' : 'OFF'),
+                '-DZSTD_BUILD_SHARED='. (getenv('SPC_STATIC_LIBS') ? 'OFF' : 'ON'),
             )
             ->build();
-        $this->patchPkgconfPrefix(['libzstd.pc']);
+        $this->patchPkgconfPrefix();
     }
 }
diff --git a/src/SPC/util/PkgConfigUtil.php b/src/SPC/util/PkgConfigUtil.php
index 4b7dfc4d..0a9e1138 100644
--- a/src/SPC/util/PkgConfigUtil.php
+++ b/src/SPC/util/PkgConfigUtil.php
@@ -63,7 +63,7 @@ class PkgConfigUtil
     {
         $static = getenv('SPC_STATIC_LIBS') ? '--static' : '';
         // get other things
-        $result = self::execWithResult("pkg-config $static --cflags-only-other {$pkg_config_str}");
+        $result = self::execWithResult("pkg-config {$static} --cflags-only-other {$pkg_config_str}");
         return trim($result);
     }
 
@@ -80,11 +80,11 @@ class PkgConfigUtil
     {
         // Use this instead of shell() to avoid unnecessary outputs
         $static = getenv('SPC_STATIC_LIBS') ? '--static' : '';
-        $result = self::execWithResult("pkg-config $static --libs-only-l {$pkg_config_str}");
+        $result = self::execWithResult("pkg-config {$static} --libs-only-l {$pkg_config_str}");
         $libs = explode(' ', trim($result));
 
         // get other things
-        $result = self::execWithResult("pkg-config $static --libs-only-other {$pkg_config_str}");
+        $result = self::execWithResult("pkg-config {$static} --libs-only-other {$pkg_config_str}");
         // convert libxxx.a to -L{path} -lxxx
         $exp = explode(' ', trim($result));
         foreach ($exp as $item) {
diff --git a/src/SPC/util/executor/UnixAutoconfExecutor.php b/src/SPC/util/executor/UnixAutoconfExecutor.php
index 877eeb30..6f98cb77 100644
--- a/src/SPC/util/executor/UnixAutoconfExecutor.php
+++ b/src/SPC/util/executor/UnixAutoconfExecutor.php
@@ -134,7 +134,7 @@ class UnixAutoconfExecutor extends Executor
     {
         return [
             getenv('SPC_STATIC_LIBS') ? '--disable-shared' : '--enable-shared',
-            getenv('SPC_STATIC_LIBS') ? '--enable-static' : '--disable-static',
+            getenv('SPC_STATIC_LIBS') ? '--enable-static' : '--enable-static', // TODO: not always static
             "--prefix={$this->library->getBuildRootPath()}",
             '--with-pic',
             '--enable-pic',