diff --git a/pjlib/include/pj/compat/os_linux.h b/pjlib/include/pj/compat/os_linux.h
index ab26852..24faa22 100644
--- a/pjlib/include/pj/compat/os_linux.h
+++ b/pjlib/include/pj/compat/os_linux.h
@@ -76,7 +76,9 @@
 
 #define PJ_HAS_HIGH_RES_TIMER	    1
 #define PJ_HAS_MALLOC               1
-#define PJ_OS_HAS_CHECK_STACK	    0
+#ifndef PJ_OS_HAS_CHECK_STACK
+#   define PJ_OS_HAS_CHECK_STACK    0
+#endif
 #define PJ_NATIVE_STRING_IS_UNICODE 0
 
 #define PJ_ATOMIC_VALUE_TYPE	    long
diff --git a/pjlib/include/pj/compat/os_linux_kernel.h b/pjlib/include/pj/compat/os_linux_kernel.h
index 11e22da..502d5aa 100644
--- a/pjlib/include/pj/compat/os_linux_kernel.h
+++ b/pjlib/include/pj/compat/os_linux_kernel.h
@@ -94,7 +94,8 @@
 #define PJ_HAS_SEMAPHORE	    0
 #define PJ_HAS_EVENT_OBJ	    0
 #define PJ_HAS_HIGH_RES_TIMER	    1
-#define PJ_OS_HAS_CHECK_STACK	    0
+#ifndef PJ_OS_HAS_CHECK_STACK
+#   define PJ_OS_HAS_CHECK_STACK    0
 #define PJ_TERM_HAS_COLOR	    0
 #define PJ_NATIVE_STRING_IS_UNICODE 0
 
diff --git a/pjlib/include/pj/compat/os_palmos.h b/pjlib/include/pj/compat/os_palmos.h
index 3d540a3..e97cd66 100644
--- a/pjlib/include/pj/compat/os_palmos.h
+++ b/pjlib/include/pj/compat/os_palmos.h
@@ -70,11 +70,12 @@
 
 /* Default threading is enabled, unless it's overridden. */
 #ifndef PJ_HAS_THREADS
-#  define PJ_HAS_THREADS	    (1)
+#  define PJ_HAS_THREADS		(1)
 #endif
 
-#define PJ_HAS_HIGH_RES_TIMER	    1
-#define PJ_OS_HAS_CHECK_STACK	    0
-#define PJ_NATIVE_STRING_IS_UNICODE 0
+#define PJ_HAS_HIGH_RES_TIMER		1
+#ifndef PJ_OS_HAS_CHECK_STACK
+#   define PJ_OS_HAS_CHECK_STACK	0
+#define PJ_NATIVE_STRING_IS_UNICODE	0
 
 #endif	/* __PJ_COMPAT_OS_PALMOS_H__ */
diff --git a/pjlib/include/pj/compat/os_sunos.h b/pjlib/include/pj/compat/os_sunos.h
index 269631f..bbe7a75 100644
--- a/pjlib/include/pj/compat/os_sunos.h
+++ b/pjlib/include/pj/compat/os_sunos.h
@@ -71,15 +71,17 @@
 
 /* Default threading is enabled, unless it's overridden. */
 #ifndef PJ_HAS_THREADS
-#  define PJ_HAS_THREADS	    (1)
+#  define PJ_HAS_THREADS		(1)
 #endif
 
-#define PJ_HAS_HIGH_RES_TIMER	    1
-#define PJ_HAS_MALLOC               1
-#define PJ_OS_HAS_CHECK_STACK	    0
-#define PJ_NATIVE_STRING_IS_UNICODE 0
+#define PJ_HAS_HIGH_RES_TIMER		1
+#define PJ_HAS_MALLOC			1
+#ifndef PJ_OS_HAS_CHECK_STACK
+#   define PJ_OS_HAS_CHECK_STACK        0
+#endif
+#define PJ_NATIVE_STRING_IS_UNICODE	0
 
-#define PJ_ATOMIC_VALUE_TYPE	    long
+#define PJ_ATOMIC_VALUE_TYPE		long
 
 /* Get BSD related identifers in Sun's include files */
 #define BSD_COMP
diff --git a/pjlib/include/pj/compat/os_win32.h b/pjlib/include/pj/compat/os_win32.h
index a078a7e..8e4c7ab 100644
--- a/pjlib/include/pj/compat/os_win32.h
+++ b/pjlib/include/pj/compat/os_win32.h
@@ -75,14 +75,16 @@
 
 /* Default threading is enabled, unless it's overridden. */
 #ifndef PJ_HAS_THREADS
-#  define PJ_HAS_THREADS	    (1)
+#  define PJ_HAS_THREADS		(1)
 #endif
 
-#define PJ_HAS_HIGH_RES_TIMER	    1
-#define PJ_HAS_MALLOC               1
-#define PJ_OS_HAS_CHECK_STACK	    1
-#define PJ_NATIVE_STRING_IS_UNICODE 0
+#define PJ_HAS_HIGH_RES_TIMER		1
+#define PJ_HAS_MALLOC			1
+#ifndef PJ_OS_HAS_CHECK_STACK
+#   define PJ_OS_HAS_CHECK_STACK	1
+#endif
+#define PJ_NATIVE_STRING_IS_UNICODE	0
 
-#define PJ_ATOMIC_VALUE_TYPE	    long
+#define PJ_ATOMIC_VALUE_TYPE		long
 
 #endif	/* __PJ_COMPAT_OS_WIN32_H__ */