diff --git a/lib/libthr/arch/aarch64/include/pthread_md.h b/lib/libthr/arch/aarch64/include/pthread_md.h
--- a/lib/libthr/arch/aarch64/include/pthread_md.h
+++ b/lib/libthr/arch/aarch64/include/pthread_md.h
@@ -41,6 +41,9 @@
 
 #define	CPU_SPINWAIT
 
+/* For use in _Static_assert to check structs will fit in a page */
+#define	THR_PAGE_SIZE_MIN	PAGE_SIZE_4K
+
 static __inline struct pthread *
 _get_curthread(void)
 {
diff --git a/lib/libthr/arch/amd64/include/pthread_md.h b/lib/libthr/arch/amd64/include/pthread_md.h
--- a/lib/libthr/arch/amd64/include/pthread_md.h
+++ b/lib/libthr/arch/amd64/include/pthread_md.h
@@ -41,6 +41,9 @@
 
 #define	CPU_SPINWAIT		__asm __volatile("pause")
 
+/* For use in _Static_assert to check structs will fit in a page */
+#define	THR_PAGE_SIZE_MIN	PAGE_SIZE
+
 static __inline struct pthread *
 _get_curthread(void)
 {
diff --git a/lib/libthr/arch/arm/include/pthread_md.h b/lib/libthr/arch/arm/include/pthread_md.h
--- a/lib/libthr/arch/arm/include/pthread_md.h
+++ b/lib/libthr/arch/arm/include/pthread_md.h
@@ -39,6 +39,9 @@
 
 #define	CPU_SPINWAIT
 
+/* For use in _Static_assert to check structs will fit in a page */
+#define	THR_PAGE_SIZE_MIN	PAGE_SIZE
+
 static __inline struct pthread *
 _get_curthread(void)
 {
diff --git a/lib/libthr/arch/i386/include/pthread_md.h b/lib/libthr/arch/i386/include/pthread_md.h
--- a/lib/libthr/arch/i386/include/pthread_md.h
+++ b/lib/libthr/arch/i386/include/pthread_md.h
@@ -41,6 +41,9 @@
 
 #define	CPU_SPINWAIT		__asm __volatile("pause")
 
+/* For use in _Static_assert to check structs will fit in a page */
+#define	THR_PAGE_SIZE_MIN	PAGE_SIZE
+
 static __inline struct pthread *
 _get_curthread(void)
 {
diff --git a/lib/libthr/arch/powerpc/include/pthread_md.h b/lib/libthr/arch/powerpc/include/pthread_md.h
--- a/lib/libthr/arch/powerpc/include/pthread_md.h
+++ b/lib/libthr/arch/powerpc/include/pthread_md.h
@@ -40,6 +40,9 @@
 
 #define	CPU_SPINWAIT
 
+/* For use in _Static_assert to check structs will fit in a page */
+#define	THR_PAGE_SIZE_MIN	PAGE_SIZE
+
 static __inline struct pthread *
 _get_curthread(void)
 {
diff --git a/lib/libthr/arch/riscv/include/pthread_md.h b/lib/libthr/arch/riscv/include/pthread_md.h
--- a/lib/libthr/arch/riscv/include/pthread_md.h
+++ b/lib/libthr/arch/riscv/include/pthread_md.h
@@ -46,6 +46,9 @@
 
 #define	CPU_SPINWAIT
 
+/* For use in _Static_assert to check structs will fit in a page */
+#define	THR_PAGE_SIZE_MIN	PAGE_SIZE
+
 static __inline struct pthread *
 _get_curthread(void)
 {
diff --git a/lib/libthr/thread/thr_barrier.c b/lib/libthr/thread/thr_barrier.c
--- a/lib/libthr/thread/thr_barrier.c
+++ b/lib/libthr/thread/thr_barrier.c
@@ -37,7 +37,7 @@
 
 #include "thr_private.h"
 
-_Static_assert(sizeof(struct pthread_barrier) <= PAGE_SIZE,
+_Static_assert(sizeof(struct pthread_barrier) <= THR_PAGE_SIZE_MIN,
     "pthread_barrier is too large for off-page");
 
 __weak_reference(_pthread_barrier_init,		pthread_barrier_init);
diff --git a/lib/libthr/thread/thr_cond.c b/lib/libthr/thread/thr_cond.c
--- a/lib/libthr/thread/thr_cond.c
+++ b/lib/libthr/thread/thr_cond.c
@@ -43,7 +43,7 @@
 
 #include "thr_private.h"
 
-_Static_assert(sizeof(struct pthread_cond) <= PAGE_SIZE,
+_Static_assert(sizeof(struct pthread_cond) <= THR_PAGE_SIZE_MIN,
     "pthread_cond too large");
 
 /*
diff --git a/lib/libthr/thread/thr_malloc.c b/lib/libthr/thread/thr_malloc.c
--- a/lib/libthr/thread/thr_malloc.c
+++ b/lib/libthr/thread/thr_malloc.c
@@ -51,8 +51,7 @@
 		return;
 	npagesizes = getpagesizes(pagesizes_d, nitems(pagesizes_d));
 	if (npagesizes == -1) {
-		npagesizes = 1;
-		pagesizes_d[0] = PAGE_SIZE;
+		PANIC("Unable to read page sizes");
 	}
 	pagesizes = pagesizes_d;
 	_thr_umutex_init(&thr_malloc_umtx);
diff --git a/lib/libthr/thread/thr_mutex.c b/lib/libthr/thread/thr_mutex.c
--- a/lib/libthr/thread/thr_mutex.c
+++ b/lib/libthr/thread/thr_mutex.c
@@ -53,7 +53,7 @@
 
 #include "thr_private.h"
 
-_Static_assert(sizeof(struct pthread_mutex) <= PAGE_SIZE,
+_Static_assert(sizeof(struct pthread_mutex) <= THR_PAGE_SIZE_MIN,
     "pthread_mutex is too large for off-page");
 
 /*
diff --git a/lib/libthr/thread/thr_pshared.c b/lib/libthr/thread/thr_pshared.c
--- a/lib/libthr/thread/thr_pshared.c
+++ b/lib/libthr/thread/thr_pshared.c
@@ -50,12 +50,17 @@
 #define	PSHARED_KEY_HASH(key)	(((unsigned long)(key) >> 8) % HASH_SIZE)
 /* XXXKIB: lock could be split to per-hash chain, if appears contested */
 static struct urwlock pshared_lock = DEFAULT_URWLOCK;
+static int page_size;
 
 void
 __thr_pshared_init(void)
 {
 	int i;
 
+	page_size = getpagesize();
+	THR_ASSERT(page_size >= THR_PAGE_SIZE_MIN,
+	    "THR_PAGE_SIZE_MIN is too large");
+
 	_thr_urwlock_init(&pshared_lock);
 	for (i = 0; i < HASH_SIZE; i++)
 		LIST_INIT(&pshared_hash[i]);
@@ -112,7 +117,7 @@
 			if (error == 0)
 				continue;
 			LIST_REMOVE(h, link);
-			munmap(h->val, PAGE_SIZE);
+			munmap(h->val, page_size);
 			free(h);
 		}
 	}
@@ -164,7 +169,7 @@
 		 */
 		if (h->key == key) {
 			if (h->val != *val) {
-				munmap(*val, PAGE_SIZE);
+				munmap(*val, page_size);
 				*val = h->val;
 			}
 			return (1);
@@ -204,7 +209,7 @@
 {
 
 	if (val != NULL)
-		munmap(val, PAGE_SIZE);
+		munmap(val, page_size);
 	_umtx_op(NULL, UMTX_OP_SHM, UMTX_SHM_DESTROY, key, NULL);
 }
 
@@ -225,7 +230,7 @@
 	    UMTX_SHM_LOOKUP, key, NULL);
 	if (fd == -1)
 		return (NULL);
-	res = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	res = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 	close(fd);
 	if (res == MAP_FAILED)
 		return (NULL);
diff --git a/lib/libthr/thread/thr_pspinlock.c b/lib/libthr/thread/thr_pspinlock.c
--- a/lib/libthr/thread/thr_pspinlock.c
+++ b/lib/libthr/thread/thr_pspinlock.c
@@ -41,7 +41,7 @@
 
 #include "thr_private.h"
 
-_Static_assert(sizeof(struct pthread_spinlock) <= PAGE_SIZE,
+_Static_assert(sizeof(struct pthread_spinlock) <= THR_PAGE_SIZE_MIN,
     "pthread_spinlock is too large for off-page");
 
 #define SPIN_COUNT 100000
diff --git a/lib/libthr/thread/thr_rwlock.c b/lib/libthr/thread/thr_rwlock.c
--- a/lib/libthr/thread/thr_rwlock.c
+++ b/lib/libthr/thread/thr_rwlock.c
@@ -38,7 +38,7 @@
 #include "un-namespace.h"
 #include "thr_private.h"
 
-_Static_assert(sizeof(struct pthread_rwlock) <= PAGE_SIZE,
+_Static_assert(sizeof(struct pthread_rwlock) <= THR_PAGE_SIZE_MIN,
     "pthread_rwlock is too large for off-page");
 
 __weak_reference(_thr_rwlock_destroy, pthread_rwlock_destroy);