diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 3775bdf..62b3acb 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -53,7 +53,7 @@ jobs:
           mkdir -p out
           VER=${{ github.ref_type == 'tag' && github.ref_name || (github.event.inputs.version != '' && github.event.inputs.version || 'dev') }}
           VER=${VER#v}
-          ${{ matrix.cc }} -O2 -Wall -static -std=c11 -D_FORTIFY_SOURCE=0 -U_FORTIFY_SOURCE -DPMM_VERSION=\"$VER\" -o out/${{ matrix.bin }} \
+          ${{ matrix.cc }} -O2 -Wall -static -std=c11 -D_GNU_SOURCE -D_FORTIFY_SOURCE=0 -U_FORTIFY_SOURCE -DPMM_VERSION=\"$VER\" -o out/${{ matrix.bin }} \
             src/main.c src/json.c src/ini.c src/pmm.c src/http.c src/repo.c src/install.c \
             src/sha256.c src/sha1.c src/mirrors.c src/pdm.c src/out.c src/i18n.c
 
diff --git a/CHANGELOG/0.3.7.md b/CHANGELOG/0.3.7.md
new file mode 100644
index 0000000..38b4359
--- /dev/null
+++ b/CHANGELOG/0.3.7.md
@@ -0,0 +1,13 @@
+# PMM v0.3.7
+
+## 修复
+- **安装/升级 `pmm` 自身后「不生效」**：之前新二进制只装进 `~/.pmm/root`,从不覆盖当前正在运行的 pmm 路径,
+  导致 apt 装的 `/usr/local/bin/pmm` 一直挡在前面、或升级后需 `hash -r` 才生效。现在安装 `pmm` 包时会把新二进制
+  **同步覆盖到当前运行的 pmm 路径**（如 `/usr/local/bin/pmm`）并自动执行 `hash -r`，`pmm -v` 立即显示新版本。
+- Windows 上 `pmm_add_to_path` 由 **append** 改为 **prepend**：PMM 目录排在 PATH 前面，避免被 `/usr/local/bin`
+  等系统目录覆盖（与 Linux 的 `~/.bashrc` 行为一致）。
+- 构建命令增加 `-D_GNU_SOURCE`，修复新版 gcc 下 `strdup`/`popen`/`realpath` 的隐式声明编译错误。
+
+## 说明
+- 若运行用户无权限覆盖 `/usr/local/bin/pmm`（非 root），会打印黄色提示：新版本位于
+  `~/.pmm/root/usr/local/bin/pmm`，请将其加入 PATH 并在当前 shell 运行 `hash -r`。
diff --git a/src/i18n.c b/src/i18n.c
index 120d069..fe8a8b4 100644
--- a/src/i18n.c
+++ b/src/i18n.c
@@ -55,6 +55,7 @@ static const char *kBuiltinZh =
 "\"msg.checksum-ok\":\"%s 校验 OK: %s\",\"msg.checksum-mismatch\":\"校验不匹配 (%s)!\","
 "\"msg.resolving-dep\":\"正在解析依赖 %s\",\"msg.registry-ok\":\"注册表 sha256 OK: %s\","
 "\"msg.path-exists\":\"PATH 已包含 PMM 目录\",\"msg.err.registry-not-found\":\"找不到软件包 '%s'\","
+"\"msg.pmm-self-replaced\":\"pmm 已更新到 %s\",\"msg.pmm-self-hint\":\"无法覆盖 %s（需 root/管理员）;新版本在 %s。请将其加入 PATH 并在当前 shell 运行 hash -r\","
 "\"msg.err.usage\":\"用法\",\"msg.err.unknown-cmd\":\"未知命令 '%s' (试试 'pmm help')\","
 "\"msg.err.download-failed\":\"下载语言包 %s 失败\",\"msg.err.invalid-locale\":\"无效语言 %s\","
 "\"msg.err.not-found\":\"找不到软件包 '%s'\",\"msg.err.failed-install\":\"安装 %s 失败\","
diff --git a/src/pdm.c b/src/pdm.c
index 5385152..8b7b38b 100644
--- a/src/pdm.c
+++ b/src/pdm.c
@@ -393,6 +393,51 @@ static void restore_aside(const char *target) {
     rename(old, target);
 }
 
+/* Locate the freshly-installed pmm binary under `root`. Fills `out` with the
+ * full path and returns 0 on success, 1 if it couldn't be found. */
+static int find_pmm_binary(const char *root, char *out, size_t outsz) {
+#ifdef _WIN32
+    const char *names[] = { "pmm.exe", "pmm" };
+#else
+    const char *names[] = { "pmm" };
+#endif
+    const char *dirms[] = { "/bin", "/usr/local/bin", "/", NULL };
+    for (int d = 0; dirms[d]; d++) {
+        for (size_t k = 0; k < sizeof(names) / sizeof(names[0]); k++) {
+            snprintf(out, outsz, "%s%s/%s", root, dirms[d], names[k]);
+            struct stat st;
+            if (stat(out, &st) == 0 && S_ISREG(st.st_mode)) return 0;
+        }
+    }
+    return 1;
+}
+
+/* After installing/upgrading the `pmm` tool itself, make the newly installed
+ * binary take effect immediately: copy it over the currently-running pmm
+ * (so an apt/system /usr/local/bin/pmm is replaced) and clear the shell's
+ * command hash so `pmm -v` reflects the new version without `hash -r`. */
+static void pmm_sync_self(const char *newbin) {
+    const char *self = pmm_self_path();
+    if (!self || !*self) return;
+    if (path_eq_ci(newbin, self)) return;          /* already the running image */
+    int moved = move_self_aside(self);
+    if (copy_file(newbin, self) != 0) {
+        if (moved) restore_aside(self);            /* put the old image back */
+        pmm_warn("%s", pmm_tr_fmt("msg.pmm-self-hint", self, newbin, newbin));
+        return;
+    }
+    if (moved) {
+        char old[1500];
+        snprintf(old, sizeof(old), "%s.old", self);
+        remove(old);                               /* drop the old image */
+    }
+    pmm_success("%s", pmm_tr_fmt("msg.pmm-self-replaced", self));
+#ifndef _WIN32
+    { char cx[1600]; snprintf(cx, sizeof(cx), "chmod +x \"%s\" 2>/dev/null || true", self); system(cx); }
+    system("hash -r 2>/dev/null || true");
+#endif
+}
+
 int pdm_info(const char *pdmfile) {
     pmm_info("%s\n", base_name(pdmfile));
     /* Copy into the pm dir + chdir, then use relative names (works with both
@@ -576,6 +621,15 @@ int pdm_install_file(const char *pdmfile) {
     }
 #endif
 
+    /* If we just installed/upgraded the pmm tool itself, make the new binary
+     * take effect immediately: replace the running image and clear the hash.
+     * (Otherwise an apt/system /usr/local/bin/pmm keeps shadowing it.) */
+    if (pkg && strcmp(pkg, "pmm") == 0) {
+        char nb[1400];
+        if (find_pmm_binary(root, nb, sizeof(nb)) == 0)
+            pmm_sync_self(nb);
+    }
+
     free(pkg); if (ver) free(ver);
     return 0;
 }
diff --git a/src/pmm.c b/src/pmm.c
index 33963d6..b2cc258 100644
--- a/src/pmm.c
+++ b/src/pmm.c
@@ -393,26 +393,30 @@ void pmm_add_to_path(void) {
     }
 #endif
 
-    /* append missing dirs (bounds-safe: never let size_t underflow) */
-    char next[17000] = "";
-    snprintf(next, sizeof(next), "%s", cur);
+    /* prepend any missing PMM dirs so they take priority over /usr/local/bin
+     * (an apt/system install could otherwise shadow a pmm-managed binary). */
+    char prefix[17000] = "";
+    size_t plen = 0;
     int added = 0;
     for (int i = 0; i < n; i++) {
         if (!list[i][0]) continue;
-        if (path_has(next, list[i], ';') || path_has(next, list[i], ':')) continue;
-        size_t l = strlen(next);
-        /* ensure a separator between entries */
-        if (l && next[l-1] != ';' && next[l-1] != ':' && l + 1 < sizeof(next)) {
-            next[l] = ';'; next[l+1] = '\0'; l++;
-        }
-        size_t room = sizeof(next) - l - 1;
+        if (path_has(cur, list[i], ';') || path_has(cur, list[i], ':')
+            || path_has(prefix, list[i], ';') || path_has(prefix, list[i], ':')) continue;
+        if (plen) { if (plen + 1 < sizeof(prefix)) prefix[plen++] = ';'; }
+        size_t room = sizeof(prefix) - plen - 1;
         if (room <= 0) break;                 /* no space left: stop */
-        snprintf(next + l, room + 1, "%s", list[i]);
+        snprintf(prefix + plen, room + 1, "%s", list[i]);
+        plen += strlen(list[i]);
         added++;
         pmm_info("%s", pmm_tr_fmt("msg.path-adding", list[i]));
     }
     if (!added) { pmm_info(pmm_tr("msg.path-exists")); return; }
 
+    /* final value: PMM dirs (prefix) then the existing startup PATH (cur).
+     * Only Windows persists it (setx); Linux prepends via .bashrc below. */
+    char next[17000] = "";
+    snprintf(next, sizeof(next), "%s;%s", prefix, cur);
+
 #ifdef _WIN32
     {
         char cmd[17001];