diff --git a/.github/workflows/freertos-mem-track.yml b/.github/workflows/freertos-mem-track.yml
new file mode 100644
index 0000000000..8870b903c1
--- /dev/null
+++ b/.github/workflows/freertos-mem-track.yml
@@ -0,0 +1,35 @@
+name: FreeRTOS mem_track.h compile regression
+
+# START OF COMMON SECTION
+on:
+  push:
+    branches: [ 'master', 'main', 'release/**' ]
+  pull_request:
+    branches: [ '*' ]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+# END OF COMMON SECTION
+
+# Regression test for the memLock / pthread.h guard misalignment in
+# wolfssl/wolfcrypt/mem_track.h that previously broke multi-threaded
+# FreeRTOS-class builds with WOLFSSL_TRACK_MEMORY + USE_WOLFSSL_MEMORY
+# + !WOLFSSL_STATIC_MEMORY. The bug was preprocessor-only, so the test
+# simulates a non-Linux/Mac/Zephyr target by suppressing the host
+# platform autodefines (-U__linux__ -U__MACH__ -U__ZEPHYR__) and using
+# the clean-room FreeRTOS.h / semphr.h stubs under
+# tests/freertos-mem-track-repro/. No cross compiler needed.
+
+jobs:
+  freertos_mem_track:
+    name: mem_track.h non-Linux multi-threaded compile
+    if: github.repository_owner == 'wolfssl'
+    runs-on: ubuntu-24.04
+    timeout-minutes: 5
+    steps:
+      - name: Checkout wolfSSL
+        uses: actions/checkout@v4
+
+      - name: Run mem_track.h FreeRTOS reproducer
+        run: sh tests/freertos-mem-track-repro/run.sh
diff --git a/tests/freertos-mem-track-repro/FreeRTOS.h b/tests/freertos-mem-track-repro/FreeRTOS.h
new file mode 100644
index 0000000000..dca2345f9e
--- /dev/null
+++ b/tests/freertos-mem-track-repro/FreeRTOS.h
@@ -0,0 +1,38 @@
+/* FreeRTOS.h
+ *
+ * Copyright (C) 2006-2026 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL.
+ *
+ * wolfSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+ */
+
+/* Stub FreeRTOS.h for the mem_track.h reproducer.
+ *
+ * Provides the minimum typedefs the wolfSSL header chain needs while
+ * pretending to be a non-Linux multi-threaded FreeRTOS target. */
+#ifndef WOLFSSL_REPRO_FREERTOS_H
+#define WOLFSSL_REPRO_FREERTOS_H
+
+typedef void *SemaphoreHandle_t;
+typedef void *xSemaphoreHandle;
+typedef void *TaskHandle_t;
+
+/* mem_track.h calls these directly under #ifdef FREERTOS. Declarations
+ * only; the test compiles -c and never links. */
+extern void *pvPortMalloc(unsigned long size);
+extern void  vPortFree(void *ptr);
+
+#endif
diff --git a/tests/freertos-mem-track-repro/repro.c b/tests/freertos-mem-track-repro/repro.c
new file mode 100644
index 0000000000..ce0d685370
--- /dev/null
+++ b/tests/freertos-mem-track-repro/repro.c
@@ -0,0 +1,30 @@
+/* repro.c
+ *
+ * Copyright (C) 2006-2026 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL.
+ *
+ * wolfSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+ */
+
+/* Reproduces the memLock / pthread.h compile failure reported by the
+ * FreeRTOS/Xtensa customer in wolfSSL 5.9.1. The bug is preprocessor-only
+ * so it triggers on any host once __linux__/__MACH__/__ZEPHYR__ are
+ * suppressed via -U flags. WOLFSSL_USER_SETTINGS is supplied by run.sh. */
+#include "user_settings.h"
+#include "wolfssl/wolfcrypt/settings.h"
+#include "wolfssl/wolfcrypt/mem_track.h"
+
+int main(void) { return 0; }
diff --git a/tests/freertos-mem-track-repro/run.sh b/tests/freertos-mem-track-repro/run.sh
new file mode 100755
index 0000000000..61d877e369
--- /dev/null
+++ b/tests/freertos-mem-track-repro/run.sh
@@ -0,0 +1,48 @@
+#!/bin/sh
+# run.sh
+#
+# Copyright (C) 2006-2026 wolfSSL Inc.
+#
+# This file is part of wolfSSL.
+#
+# wolfSSL is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# wolfSSL is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+
+# Regression test for the mem_track.h memLock guard misalignment that
+# previously broke multi-threaded FreeRTOS-class builds with
+# WOLFSSL_TRACK_MEMORY + USE_WOLFSSL_MEMORY + !WOLFSSL_STATIC_MEMORY.
+#
+# The bug is preprocessor-only, so the test runs on a stock Linux host:
+#   -U__linux__ -U__MACH__ -U__ZEPHYR__ suppresses the host autodefines
+#   that would otherwise hide it. Stub FreeRTOS.h / semphr.h satisfy the
+#   wc_port.h FREERTOS_TCP mutex typedef without needing a real RTOS.
+#
+# Exit 0 = mem_track.h still compiles in the non-Linux multi-threaded
+# config, i.e. the fix is in place. Exit non-zero = the misalignment is
+# back. Run from the wolfssl repo root.
+set -u
+cc -DWOLFSSL_USER_SETTINGS \
+    -U__linux__ -U__MACH__ -U__ZEPHYR__ \
+    -I tests/freertos-mem-track-repro \
+    -I . \
+    -c tests/freertos-mem-track-repro/repro.c \
+    -o /dev/null
+status=$?
+if [ $status -eq 0 ]; then
+    echo "OK: mem_track.h compiles for non-Linux multi-threaded config."
+else
+    echo "FAIL: mem_track.h compile broken for non-Linux multi-threaded" >&2
+    echo "      config - the memLock guard misalignment may be back." >&2
+fi
+exit $status
diff --git a/tests/freertos-mem-track-repro/semphr.h b/tests/freertos-mem-track-repro/semphr.h
new file mode 100644
index 0000000000..8526b1a678
--- /dev/null
+++ b/tests/freertos-mem-track-repro/semphr.h
@@ -0,0 +1,26 @@
+/* semphr.h
+ *
+ * Copyright (C) 2006-2026 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL.
+ *
+ * wolfSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+ */
+
+/* Stub semphr.h for the mem_track.h reproducer. SemaphoreHandle_t is
+ * declared in the stub FreeRTOS.h. */
+#ifndef WOLFSSL_REPRO_SEMPHR_H
+#define WOLFSSL_REPRO_SEMPHR_H
+#endif
diff --git a/tests/freertos-mem-track-repro/task.h b/tests/freertos-mem-track-repro/task.h
new file mode 100644
index 0000000000..78862f96d2
--- /dev/null
+++ b/tests/freertos-mem-track-repro/task.h
@@ -0,0 +1,27 @@
+/* task.h
+ *
+ * Copyright (C) 2006-2026 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL.
+ *
+ * wolfSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+ */
+
+/* Stub task.h for the mem_track.h reproducer. The wolfSSL header chain
+ * includes this when FREERTOS is defined; we don't need any of the real
+ * task API to reach the mem_track.h code under test. */
+#ifndef WOLFSSL_REPRO_TASK_H
+#define WOLFSSL_REPRO_TASK_H
+#endif
diff --git a/tests/freertos-mem-track-repro/user_settings.h b/tests/freertos-mem-track-repro/user_settings.h
new file mode 100644
index 0000000000..a864f622cd
--- /dev/null
+++ b/tests/freertos-mem-track-repro/user_settings.h
@@ -0,0 +1,38 @@
+/* user_settings.h
+ *
+ * Copyright (C) 2006-2026 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL.
+ *
+ * wolfSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+ */
+
+/* Minimal user_settings.h reproducing the bug state. */
+#ifndef WOLFSSL_FREERTOS_MEM_TRACK_REPRO_USER_SETTINGS_H
+#define WOLFSSL_FREERTOS_MEM_TRACK_REPRO_USER_SETTINGS_H
+
+#define FREERTOS
+#define FREERTOS_TCP
+#define NO_FILESYSTEM
+#define WOLFSSL_NO_SOCK
+#define USE_WOLFSSL_MEMORY
+#define WOLFSSL_TRACK_MEMORY
+#define WOLFSSL_DEBUG_MEMORY
+#define WOLFSSL_DEBUG_MEMORY_PRINT
+#define DEBUG_WOLFSSL
+
+/* Intentionally NOT defined: SINGLE_THREADED, WOLFSSL_STATIC_MEMORY */
+
+#endif
diff --git a/tests/include.am b/tests/include.am
index 8dcdf3a0c6..b512f72449 100644
--- a/tests/include.am
+++ b/tests/include.am
@@ -88,5 +88,11 @@ EXTRA_DIST += tests/unit.h \
               tests/emnet/IP/IP.h \
               tests/emnet/emnet_shim.c \
               tests/emnet/emnet_nonblock_test.c \
-              tests/emnet/Makefile
+              tests/emnet/Makefile \
+              tests/freertos-mem-track-repro/user_settings.h \
+              tests/freertos-mem-track-repro/repro.c \
+              tests/freertos-mem-track-repro/FreeRTOS.h \
+              tests/freertos-mem-track-repro/semphr.h \
+              tests/freertos-mem-track-repro/task.h \
+              tests/freertos-mem-track-repro/run.sh
 DISTCLEANFILES+= tests/.libs/unit.test
diff --git a/wolfssl/wolfcrypt/mem_track.h b/wolfssl/wolfcrypt/mem_track.h
index 7046731fb2..daef2753df 100644
--- a/wolfssl/wolfcrypt/mem_track.h
+++ b/wolfssl/wolfcrypt/mem_track.h
@@ -142,9 +142,12 @@ static memoryStats ourMemStats;
 WOLFSSL_API extern memoryStats *wc_MemStats_Ptr;
 
 #ifdef DO_MEM_LIST
-    #include <pthread.h>
     static memoryList ourMemList;
-    static pthread_mutex_t memLock = PTHREAD_MUTEX_INITIALIZER;
+#endif
+
+#if !defined(SINGLE_THREADED) && (defined(DO_MEM_LIST) || defined(DO_MEM_STATS))
+    static wolfSSL_Mutex memLock;
+    static int memLockInit = 0;
 #endif
 
 #ifdef WOLFSSL_DEBUG_MEMORY
@@ -182,7 +185,7 @@ static WC_INLINE void* TrackMalloc(size_t sz)
 #endif
 #endif
 #if !defined(SINGLE_THREADED) && (defined(DO_MEM_LIST) || defined(DO_MEM_STATS))
-    if (pthread_mutex_lock(&memLock) == 0)
+    if (wc_LockMutex(&memLock) == 0)
     {
 #endif
 
@@ -228,9 +231,9 @@ static WC_INLINE void* TrackMalloc(size_t sz)
         ourMemList.count++;
 #endif
 #if !defined(SINGLE_THREADED) && (defined(DO_MEM_LIST) || defined(DO_MEM_STATS))
-        pthread_mutex_unlock(&memLock);
+        wc_UnLockMutex(&memLock);
     }
-#endif /* DO_MEM_LIST */
+#endif /* !SINGLE_THREADED && (DO_MEM_LIST || DO_MEM_STATS) */
 
     return header->thisMemory;
 }
@@ -255,7 +258,7 @@ static WC_INLINE void TrackFree(void* ptr)
     sz = header->thisSize;
 
 #if !defined(SINGLE_THREADED) && (defined(DO_MEM_LIST) || defined(DO_MEM_STATS))
-    if (pthread_mutex_lock(&memLock) == 0)
+    if (wc_LockMutex(&memLock) == 0)
     {
 #endif
 
@@ -289,7 +292,7 @@ static WC_INLINE void TrackFree(void* ptr)
 #endif
 
 #if !defined(SINGLE_THREADED) && (defined(DO_MEM_LIST) || defined(DO_MEM_STATS))
-        pthread_mutex_unlock(&memLock);
+        wc_UnLockMutex(&memLock);
     }
 #endif
 
@@ -362,14 +365,27 @@ static WC_INLINE int InitMemoryTracker(void)
     if (ret < 0) {
         wc_mem_printf("wolfSSL GetAllocators failed to get the defaults\n");
     }
+
+#if !defined(SINGLE_THREADED) && (defined(DO_MEM_LIST) || defined(DO_MEM_STATS))
+    /* Init the mutex before installing the tracking allocators, so the
+     * mutex is ready as soon as another thread can enter TrackMalloc. */
+    if (!memLockInit) {
+        if (wc_InitMutex(&memLock) != 0) {
+            wc_mem_printf("wc_InitMutex failed for track memory\n");
+            return -1;
+        }
+        memLockInit = 1;
+    }
+#endif
+
     ret = wolfSSL_SetAllocators(TrackMalloc, TrackFree, TrackRealloc);
     if (ret < 0) {
         wc_mem_printf("wolfSSL SetAllocators failed for track memory\n");
         return ret;
     }
 
-#ifdef DO_MEM_LIST
-    if (pthread_mutex_lock(&memLock) == 0)
+#if !defined(SINGLE_THREADED) && (defined(DO_MEM_LIST) || defined(DO_MEM_STATS))
+    if (wc_LockMutex(&memLock) == 0)
 #endif
     {
     #ifdef DO_MEM_STATS
@@ -387,8 +403,11 @@ static WC_INLINE int InitMemoryTracker(void)
     #ifdef DO_MEM_LIST
         XMEMSET(&ourMemList, 0, sizeof(ourMemList));
         ourMemStats.memList = &ourMemList;
+    #endif
 
-        pthread_mutex_unlock(&memLock);
+    #if !defined(SINGLE_THREADED) && \
+        (defined(DO_MEM_LIST) || defined(DO_MEM_STATS))
+        wc_UnLockMutex(&memLock);
     #endif
     }
 
@@ -399,8 +418,8 @@ static WC_INLINE int InitMemoryTracker(void)
 
 static WC_INLINE void ShowMemoryTracker(void)
 {
-#ifdef DO_MEM_LIST
-    if (pthread_mutex_lock(&memLock) == 0)
+#if !defined(SINGLE_THREADED) && (defined(DO_MEM_LIST) || defined(DO_MEM_STATS))
+    if (wc_LockMutex(&memLock) == 0)
 #endif
     {
     #ifdef DO_MEM_STATS
@@ -429,8 +448,11 @@ static WC_INLINE void ShowMemoryTracker(void)
         #endif
             }
         }
+    #endif
 
-        pthread_mutex_unlock(&memLock);
+    #if !defined(SINGLE_THREADED) && \
+        (defined(DO_MEM_LIST) || defined(DO_MEM_STATS))
+        wc_UnLockMutex(&memLock);
     #endif
     }
 }
@@ -438,7 +460,13 @@ static WC_INLINE void ShowMemoryTracker(void)
 static WC_INLINE int CleanupMemoryTracker(void)
 {
     wc_MemStats_Ptr = NULL;
-    /* restore default allocators */
+    /* Restore default allocators. memLock is intentionally left
+     * initialized for process lifetime (matching the prior static
+     * PTHREAD_MUTEX_INITIALIZER behavior): SetAllocators stops new
+     * entries into TrackMalloc/TrackFree but does not synchronize
+     * with in-flight calls, so freeing the mutex here would be a
+     * use-after-free hazard. The memLockInit flag keeps re-Init
+     * idempotent across an Init/Cleanup/Init cycle. */
     return wolfSSL_SetAllocators(mfDefault, ffDefault, rfDefault);
 }
 #endif /* WOLFSSL_TRACK_MEMORY && USE_WOLFSSL_MEMORY && \