diff --git a/pkg/urbit/bench/ur_bench.c b/pkg/urbit/bench/ur_bench.c
index 40a4e518c6..5ede7b5e92 100644
--- a/pkg/urbit/bench/ur_bench.c
+++ b/pkg/urbit/bench/ur_bench.c
@@ -7,7 +7,7 @@
 static void
 _setup(void)
 {
-  u3m_init();
+  u3m_init(1 << 23);
   u3m_pave(c3y);
 }
 
diff --git a/pkg/urbit/include/noun/allocate.h b/pkg/urbit/include/noun/allocate.h
index 529ad6fb60..964de538be 100644
--- a/pkg/urbit/include/noun/allocate.h
+++ b/pkg/urbit/include/noun/allocate.h
@@ -1,8 +1,6 @@
 #ifndef U3_ALLOCATE_H
 #define U3_ALLOCATE_H
 
-#include <openssl/opensslv.h>
-
 #include "manage.h"
 
   /**  Constants.
@@ -15,15 +13,15 @@
     */
 #     define u3a_page   12
 
-    /* u3a_pages: number of pages in memory.
+    /* u3a_pages: maximum number of pages in memory.
     */
 #     define u3a_pages  (1 << (u3a_bits - u3a_page))
 
-    /* u3a_words: number of words in memory.
+    /* u3a_words: maximum number of words in memory.
     */
 #     define u3a_words  (1 << u3a_bits)
 
-    /* u3a_bytes: number of bytes in memory.
+    /* u3a_bytes: maximum number of bytes in memory.
     */
 #     define u3a_bytes  (sizeof(c3_w) * u3a_words)
 
@@ -477,15 +475,6 @@
           void*
           u3a_malloc(size_t len_i);
 
-        /* u3a_malloc_ssl(): openssl-shaped malloc
-        */
-          void*
-          u3a_malloc_ssl(size_t len_i
-#if OPENSSL_VERSION_NUMBER >= 0x10100000L
-                          , const char* file, int line
-#endif
-                          );
-
         /* u3a_calloc(): aligned storage measured in bytes.
         */
           void*
@@ -496,39 +485,11 @@
           void*
           u3a_realloc(void* lag_v, size_t len_i);
 
-        /* u3a_realloc2(): gmp-shaped realloc.
-        */
-          void*
-          u3a_realloc2(void* lag_v, size_t old_i, size_t new_i);
-
-        /* u3a_realloc_ssl(): openssl-shaped realloc.
-        */
-          void*
-          u3a_realloc_ssl(void* lag_v, size_t len_i
-#if OPENSSL_VERSION_NUMBER >= 0x10100000L
-                          , const char* file, int line
-#endif
-                          );
-
         /* u3a_free(): free for aligned malloc.
         */
           void
           u3a_free(void* tox_v);
 
-        /* u3a_free2(): gmp-shaped free.
-        */
-          void
-          u3a_free2(void* tox_v, size_t siz_i);
-
-        /* u3a_free_ssl(): openssl-shaped free.
-        */
-          void
-          u3a_free_ssl(void* tox_v
-#if OPENSSL_VERSION_NUMBER >= 0x10100000L
-                          , const char* file, int line
-#endif
-                          );
-
       /* Reference and arena control.
       */
         /* u3a_gain(): gain a reference count in normal space.
diff --git a/pkg/urbit/include/noun/events.h b/pkg/urbit/include/noun/events.h
index 92d5c2a75e..4a27959634 100644
--- a/pkg/urbit/include/noun/events.h
+++ b/pkg/urbit/include/noun/events.h
@@ -41,6 +41,7 @@
       typedef struct _u3e_pool {
         c3_c*     dir_c;                     //  path to
         c3_w      dit_w[u3a_pages >> 5];     //  touched since last save
+        c3_w      pag_w;                     //  number of pages (<= u3a_pages)
         u3e_image nor_u;                     //  north segment
         u3e_image sou_u;                     //  south segment
       } u3e_pool;
diff --git a/pkg/urbit/include/noun/manage.h b/pkg/urbit/include/noun/manage.h
index 89f50d6037..a1ffb6495d 100644
--- a/pkg/urbit/include/noun/manage.h
+++ b/pkg/urbit/include/noun/manage.h
@@ -37,7 +37,7 @@
       /* u3m_init(): start the environment.
       */
         void
-        u3m_init();
+        u3m_init(size_t len_i);
 
       /* u3m_pave(): instantiate or activate image.
       */
diff --git a/pkg/urbit/include/noun/options.h b/pkg/urbit/include/noun/options.h
index f73dba264d..c1fd58c408 100644
--- a/pkg/urbit/include/noun/options.h
+++ b/pkg/urbit/include/noun/options.h
@@ -9,6 +9,7 @@
         u3_noun who;                          //  single identity
         c3_c*   dir_c;                        //  execution directory (pier)
         c3_w    wag_w;                        //  flags (both ways)
+        size_t  wor_i;                        //  loom word-length (<= u3a_words)
         void (*stderr_log_f)(c3_c*);          //  errors from c code
         void (*slog_f)(u3_noun);              //  function pointer for slog
         void (*sign_hold_f)(void);            //  suspend system signal regime
diff --git a/pkg/urbit/noun/allocate.c b/pkg/urbit/noun/allocate.c
index 2a92e64903..f7ce679584 100644
--- a/pkg/urbit/noun/allocate.c
+++ b/pkg/urbit/noun/allocate.c
@@ -692,18 +692,6 @@ u3a_malloc(size_t len_i)
   return out_w;
 }
 
-/* u3a_malloc_ssl(): openssl-shaped malloc
-*/
-void*
-u3a_malloc_ssl(size_t len_i
-#if OPENSSL_VERSION_NUMBER >= 0x10100000L
-               , const char* file, int line
-#endif
-               )
-{
-  return u3a_malloc(len_i);
-}
-
 /* u3a_cellblock(): allocate a block of cells on the hat.
 */
 static c3_o
@@ -885,26 +873,6 @@ u3a_realloc(void* lag_v, size_t len_i)
   return u3a_wealloc(lag_v, (len_w + 3) >> 2);
 }
 
-/* u3a_realloc2(): gmp-shaped realloc.
-*/
-void*
-u3a_realloc2(void* lag_v, size_t old_i, size_t new_i)
-{
-  return u3a_realloc(lag_v, new_i);
-}
-
-/* u3a_realloc_ssl(): openssl-shaped realloc.
-*/
-void*
-u3a_realloc_ssl(void* lag_v, size_t len_i
-#if OPENSSL_VERSION_NUMBER >= 0x10100000L
-                , const char* file, int line
-#endif
-                )
-{
-  return u3a_realloc(lag_v, len_i);
-}
-
 /* u3a_free(): free for aligned malloc.
 */
 void
@@ -921,26 +889,6 @@ u3a_free(void* tox_v)
   u3a_wfree(org_w);
 }
 
-/* u3a_free2(): gmp-shaped free.
-*/
-void
-u3a_free2(void* tox_v, size_t siz_i)
-{
-  return u3a_free(tox_v);
-}
-
-/* u3a_free_ssl(): openssl-shaped free.
-*/
-void
-u3a_free_ssl(void* tox_v
-#if OPENSSL_VERSION_NUMBER >= 0x10100000L
-             , const char* file, int line
-#endif
-             )
-{
-  return u3a_free(tox_v);
-}
-
 /* _me_wash_north(): clean up mug slots after copy.
 */
 static void _me_wash_north(u3_noun dog);
diff --git a/pkg/urbit/noun/events.c b/pkg/urbit/noun/events.c
index 6986e91a22..601e803c3c 100644
--- a/pkg/urbit/noun/events.c
+++ b/pkg/urbit/noun/events.c
@@ -136,9 +136,9 @@ u3e_check(c3_c* cap_c)
       sum_w += mug_w;
     }
     for ( i_w = 0; i_w < sou_w; i_w++ ) {
-      mug_w = _ce_check_page((u3a_pages - (i_w + 1)));
+      mug_w = _ce_check_page((u3P.pag_w - (i_w + 1)));
       if ( strcmp(cap_c, "boot") ) {
-        c3_assert(mug_w == u3K.mug_w[(u3a_pages - (i_w + 1))]);
+        c3_assert(mug_w == u3K.mug_w[(u3P.pag_w - (i_w + 1))]);
       }
       sum_w += mug_w;
     }
@@ -195,7 +195,7 @@ _ce_center_guard_page(void)
 {
   u3p(c3_w) bot_p, top_p;
   if ( !u3R ) {
-    top_p = u3a_outa(u3_Loom + u3a_words);
+    top_p = u3a_outa(u3_Loom + u3C.wor_i);
     bot_p = u3a_outa(u3_Loom);
   }
   else if ( c3y == u3a_is_north(u3R) ) {
@@ -255,9 +255,9 @@ u3e_fault(void* adr_v, c3_i ser_i)
 
   c3_w* adr_w = (c3_w*) adr_v;
 
-  if ( (adr_w < u3_Loom) || (adr_w >= (u3_Loom + u3a_words)) ) {
+  if ( (adr_w < u3_Loom) || (adr_w >= (u3_Loom + u3C.wor_i)) ) {
     fprintf(stderr, "address %p out of loom!\r\n", adr_w);
-    fprintf(stderr, "loom: [%p : %p)\r\n", u3_Loom, u3_Loom + u3a_words);
+    fprintf(stderr, "loom: [%p : %p)\r\n", u3_Loom, u3_Loom + u3C.wor_i);
     c3_assert(0);
     return 0;
   }
@@ -629,7 +629,7 @@ _ce_patch_compose(void)
       pgs_w = _ce_patch_count_page(i_w, pgs_w);
     }
     for ( i_w = 0; i_w < sou_w; i_w++ ) {
-      pgs_w = _ce_patch_count_page((u3a_pages - (i_w + 1)), pgs_w);
+      pgs_w = _ce_patch_count_page((u3P.pag_w - (i_w + 1)), pgs_w);
     }
   }
 
@@ -649,7 +649,7 @@ _ce_patch_compose(void)
       pgc_w = _ce_patch_save_page(pat_u, i_w, pgc_w);
     }
     for ( i_w = 0; i_w < sou_w; i_w++ ) {
-      pgc_w = _ce_patch_save_page(pat_u, (u3a_pages - (i_w + 1)), pgc_w);
+      pgc_w = _ce_patch_save_page(pat_u, (u3P.pag_w - (i_w + 1)), pgc_w);
     }
 
     pat_u->con_u->nor_w = nor_w;
@@ -699,7 +699,7 @@ _ce_image_resize(u3e_image* img_u, c3_w pgs_w)
 {
   if ( img_u->pgs_w > pgs_w ) {
     if ( ftruncate(img_u->fid_i, pgs_w << (u3a_page + 2)) ) {
-      fprintf(stderr, "loom: image truncate %s: %s\r\n",
+      fprintf(stderr, "loom: image (%s) truncate: %s\r\n",
                       img_u->nam_c,
                       strerror(errno));
       c3_assert(0);
@@ -745,7 +745,7 @@ _ce_patch_apply(u3_ce_patch* pat_u)
     }
     else {
       fid_i = u3P.sou_u.fid_i;
-      off_w = (u3a_pages - (pag_w + 1));
+      off_w = (u3P.pag_w - (pag_w + 1));
     }
 
     if ( -1 == read(pat_u->mem_i, mem_w, pag_siz_i) ) {
@@ -785,7 +785,8 @@ _ce_image_blit(u3e_image* img_u,
   lseek(img_u->fid_i, 0, SEEK_SET);
   for ( i_w = 0; i_w < img_u->pgs_w; i_w++ ) {
     if ( -1 == read(img_u->fid_i, ptr_w, siz_w) ) {
-      fprintf(stderr, "loom: image blit read: %s\r\n", strerror(errno));
+      fprintf(stderr, "loom: image (%s) blit read: %s\r\n",
+                      img_u->nam_c, strerror(errno));
       c3_assert(0);
     }
 
@@ -819,7 +820,9 @@ _ce_image_fine(u3e_image* img_u,
     c3_w mem_w, fil_w;
 
     if ( -1 == read(img_u->fid_i, buf_w, pag_siz_i) ) {
-      fprintf(stderr, "loom: image fine read: %s\r\n", strerror(errno));
+      fprintf(stderr, "loom: image (%s) fine read: %s\r\n",
+                      img_u->nam_c,
+                      strerror(errno));
       c3_assert(0);
     }
     mem_w = u3r_mug_words(ptr_w, pag_wiz_i);
@@ -828,11 +831,13 @@ _ce_image_fine(u3e_image* img_u,
     if ( mem_w != fil_w ) {
       c3_w pag_w = (ptr_w - u3_Loom) >> u3a_page;
 
-      fprintf(stderr, "mismatch: page %d, mem_w %x, fil_w %x, K %x\r\n",
-                     pag_w,
-                     mem_w,
-                     fil_w,
-                     u3K.mug_w[pag_w]);
+      fprintf(stderr, "loom: image (%s) mismatch: "
+                      "page %d, mem_w %x, fil_w %x, K %x\r\n",
+                      img_u->nam_c,
+                      pag_w,
+                      mem_w,
+                      fil_w,
+                      u3K.mug_w[pag_w]);
       abort();
     }
     ptr_w += stp_ws;
@@ -856,7 +861,9 @@ _ce_image_copy(u3e_image* fom_u, u3e_image* tou_u)
   if (  (-1 == lseek(fom_u->fid_i, 0, SEEK_SET))
      || (-1 == lseek(tou_u->fid_i, 0, SEEK_SET)) )
   {
-    fprintf(stderr, "loom: image copy seek 0: %s\r\n", strerror(errno));
+    fprintf(stderr, "loom: image (%s) copy seek: %s\r\n",
+                    fom_u->nam_c,
+                    strerror(errno));
     return c3n;
   }
 
@@ -867,16 +874,22 @@ _ce_image_copy(u3e_image* fom_u, u3e_image* tou_u)
     c3_w off_w = i_w;
 
     if ( -1 == read(fom_u->fid_i, mem_w, pag_siz_i) ) {
-      fprintf(stderr, "loom: image copy read: %s\r\n", strerror(errno));
+      fprintf(stderr, "loom: image (%s) copy read: %s\r\n",
+                      fom_u->nam_c,
+                      strerror(errno));
       return c3n;
     }
     else {
       if ( -1 == lseek(tou_u->fid_i, (off_w << (u3a_page + 2)), SEEK_SET) ) {
-        fprintf(stderr, "loom: image copy seek: %s\r\n", strerror(errno));
+        fprintf(stderr, "loom: image (%s) copy seek: %s\r\n",
+                        tou_u->nam_c,
+                        strerror(errno));
         return c3n;
       }
       if ( -1 == write(tou_u->fid_i, mem_w, pag_siz_i) ) {
-        fprintf(stderr, "loom: image copy write: %s\r\n", strerror(errno));
+        fprintf(stderr, "loom: image (%s) copy write: %s\r\n",
+                        tou_u->nam_c,
+                        strerror(errno));
         return c3n;
       }
     }
@@ -983,7 +996,7 @@ u3e_save(void)
                    pag_wiz_i);
 
     _ce_image_fine(&u3P.sou_u,
-                   (u3_Loom + (1 << u3a_bits) - pag_wiz_i),
+                   (u3_Loom + u3C.wor_i) - pag_wiz_i,
                    -(ssize_t)pag_wiz_i);
 
     c3_assert(u3P.nor_u.pgs_w == u3K.nor_w);
@@ -1011,6 +1024,7 @@ u3e_live(c3_o nuu_o, c3_c* dir_c)
   u3P.dir_c = dir_c;
   u3P.nor_u.nam_c = "north";
   u3P.sou_u.nam_c = "south";
+  u3P.pag_w = u3C.wor_i >> u3a_page;
 
   //  XX review dryrun requirements, enable or remove
   //
@@ -1041,6 +1055,11 @@ u3e_live(c3_o nuu_o, c3_c* dir_c)
         _ce_patch_delete();
       }
 
+      if ( u3P.nor_u.pgs_w + u3P.sou_u.pgs_w >= u3P.pag_w ) {
+        fprintf(stderr, "boot: snapshot too big for loom\r\n");
+        exit(1);
+      }
+
       //  mark all pages dirty (pages in the snapshot will be marked clean)
       //
       u3e_foul();
@@ -1053,7 +1072,7 @@ u3e_live(c3_o nuu_o, c3_c* dir_c)
                        pag_wiz_i);
 
         _ce_image_blit(&u3P.sou_u,
-                       (u3_Loom + (1 << u3a_bits) - pag_wiz_i),
+                       (u3_Loom + u3C.wor_i) - pag_wiz_i,
                        -(ssize_t)pag_wiz_i);
 
         u3l_log("boot: protected loom\r\n");
@@ -1080,9 +1099,12 @@ u3e_live(c3_o nuu_o, c3_c* dir_c)
 c3_o
 u3e_yolo(void)
 {
-  //    NB: u3e_save() will reinstate protection flags
+  //  NB: u3e_save() will reinstate protection flags
   //
-  if ( 0 != mprotect((void *)u3_Loom, u3a_bytes, (PROT_READ | PROT_WRITE)) ) {
+  if ( 0 != mprotect((void *)u3_Loom,
+                     u3C.wor_i << 2,
+                     (PROT_READ | PROT_WRITE)) )
+  {
     return c3n;
   }
 
@@ -1100,6 +1122,8 @@ u3e_foul(void)
 void
 u3e_init(void)
 {
+  u3P.pag_w = u3C.wor_i >> u3a_page;
+
 #ifdef U3_GUARD_PAGE
   _ce_center_guard_page();
 #endif
diff --git a/pkg/urbit/noun/manage.c b/pkg/urbit/noun/manage.c
index 17befccf70..26f103fa70 100644
--- a/pkg/urbit/noun/manage.c
+++ b/pkg/urbit/noun/manage.c
@@ -553,7 +553,7 @@ _pave_home(void)
 {
   c3_w* mem_w = u3_Loom + 1;
   c3_w  siz_w = c3_wiseof(u3v_home);
-  c3_w  len_w = u3a_words - 1;
+  c3_w  len_w = u3C.wor_i - 1;
 
   u3H = (void *)_pave_north(mem_w, siz_w, len_w);
   u3H->ver_w = u3v_version;
@@ -574,7 +574,7 @@ _find_home(void)
   //
   c3_w* mem_w = u3_Loom + 1;
   c3_w  siz_w = c3_wiseof(u3v_home);
-  c3_w  len_w = u3a_words - 1;
+  c3_w  len_w = u3C.wor_i - 1;
 
   {
     c3_w ver_w = *((mem_w + len_w) - 1);
@@ -590,6 +590,11 @@ _find_home(void)
 
   u3H = (void *)((mem_w + len_w) - siz_w);
   u3R = &u3H->rod_u;
+
+  //  this looks risky, but there are no legitimate scenarios
+  //  where it's wrong
+  //
+  u3R->cap_p = u3R->mat_p = u3C.wor_i - c3_wiseof(*u3H);
 }
 
 /* u3m_pave(): instantiate or activate image.
@@ -1718,16 +1723,53 @@ _cm_signals(void)
 # endif
 }
 
-extern void u3je_secp_init(void);
-extern void u3je_secp_stop(void);
+/* _cm_malloc_ssl(): openssl-shaped malloc
+*/
+static void*
+_cm_malloc_ssl(size_t len_i
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+               , const char* file, int line
+#endif
+               )
+{
+  return u3a_malloc(len_i);
+}
 
+/* _cm_realloc_ssl(): openssl-shaped realloc.
+*/
+static void*
+_cm_realloc_ssl(void* lag_v, size_t len_i
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+                , const char* file, int line
+#endif
+                )
+{
+  return u3a_realloc(lag_v, len_i);
+}
+
+/* _cm_free_ssl(): openssl-shaped free.
+*/
+static void
+_cm_free_ssl(void* tox_v
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+             , const char* file, int line
+#endif
+             )
+{
+  return u3a_free(tox_v);
+}
+
+extern void u3je_secp_init(void);
+
+/* _cm_crypto(): initialize openssl and crypto jets.
+*/
 static void
 _cm_crypto()
 {
   /* Initialize OpenSSL with loom allocation functions. */
-  if ( 0 == CRYPTO_set_mem_functions(&u3a_malloc_ssl,
-                                     &u3a_realloc_ssl,
-                                     &u3a_free_ssl) ) {
+  if ( 0 == CRYPTO_set_mem_functions(&_cm_malloc_ssl,
+                                     &_cm_realloc_ssl,
+                                     &_cm_free_ssl) ) {
     u3l_log("%s\r\n", "openssl initialization failed");
     abort();
   }
@@ -1735,53 +1777,81 @@ _cm_crypto()
   u3je_secp_init();
 }
 
+/* _cm_realloc2(): gmp-shaped realloc.
+*/
+static void*
+_cm_realloc2(void* lag_v, size_t old_i, size_t new_i)
+{
+  return u3a_realloc(lag_v, new_i);
+}
+
+/* _cm_free2(): gmp-shaped free.
+*/
+static void
+_cm_free2(void* tox_v, size_t siz_i)
+{
+  return u3a_free(tox_v);
+}
+
 /* u3m_init(): start the environment.
 */
 void
-u3m_init(void)
+u3m_init(size_t len_i)
 {
   _cm_limits();
   _cm_signals();
   _cm_crypto();
 
-  /* Make sure GMP uses our malloc.
-  */
-  mp_set_memory_functions(u3a_malloc, u3a_realloc2, u3a_free2);
+  //  make sure GMP uses our malloc.
+  //
+  mp_set_memory_functions(u3a_malloc, _cm_realloc2, _cm_free2);
 
-  /* Map at fixed address.
-  */
+  //  make sure that [len_i] is a fully-addressible non-zero power of two.
+  //
+  if (  !len_i
+     || (len_i & (len_i - 1))
+     || (len_i < (1 << (u3a_page + 2)))
+     || (len_i > u3a_bytes) )
   {
-    c3_w  len_w = u3a_bytes;
-    void* map_v;
+    u3l_log("loom: bad size: %zu\r\n", len_i);
+    exit(1);
+  }
 
-    map_v = mmap((void *)u3_Loom,
-                 len_w,
-                 (PROT_READ | PROT_WRITE),
-                 (MAP_ANON | MAP_FIXED | MAP_PRIVATE),
-                 -1, 0);
+  // map at fixed address.
+  //
+  {
+    void* map_v = mmap((void *)u3_Loom,
+                       len_i,
+                       (PROT_READ | PROT_WRITE),
+                       (MAP_ANON | MAP_FIXED | MAP_PRIVATE),
+                       -1, 0);
 
     if ( -1 == (c3_ps)map_v ) {
-      void* dyn_v = mmap((void *)0,
-                         len_w,
-                         PROT_READ,
-                         MAP_ANON | MAP_PRIVATE,
-                         -1, 0);
+      map_v = mmap((void *)0,
+                   len_i,
+                   (PROT_READ | PROT_WRITE),
+                   (MAP_ANON | MAP_PRIVATE),
+                   -1, 0);
 
-      u3l_log("boot: mapping %dMB failed\r\n", (len_w / (1024 * 1024)));
+      u3l_log("boot: mapping %zuMB failed\r\n", len_i >> 20);
       u3l_log("see urbit.org/using/install/#about-swap-space"
               " for adding swap space\r\n");
-      if ( -1 != (c3_ps)dyn_v ) {
+      if ( -1 != (c3_ps)map_v ) {
         u3l_log("if porting to a new platform, try U3_OS_LoomBase %p\r\n",
-                dyn_v);
+                map_v);
       }
       exit(1);
     }
 
-    u3l_log("loom: mapped %dMB\r\n", len_w >> 20);
+    u3C.wor_i = len_i >> 2;
+    u3l_log("loom: mapped %zuMB\r\n", len_i >> 20);
   }
 }
 
-/* u3m_stop(): graceful shutdown cleanup. */
+extern void u3je_secp_stop(void);
+
+/* u3m_stop(): graceful shutdown cleanup.
+*/
 void
 u3m_stop()
 {
@@ -1797,7 +1867,7 @@ u3m_boot(c3_c* dir_c)
 
   /* Activate the loom.
   */
-  u3m_init();
+  u3m_init(u3a_bytes);
 
   /* Activate the storage system.
   */
@@ -1847,7 +1917,7 @@ u3m_boot_lite(void)
 {
   /* Activate the loom.
   */
-  u3m_init();
+  u3m_init(u3a_bytes);
 
   /* Activate tracing.
   */
diff --git a/pkg/urbit/tests/ames_tests.c b/pkg/urbit/tests/ames_tests.c
index 69ed7b9b98..0907898d41 100644
--- a/pkg/urbit/tests/ames_tests.c
+++ b/pkg/urbit/tests/ames_tests.c
@@ -6,7 +6,7 @@
 static void
 _setup(void)
 {
-  u3m_init();
+  u3m_init(1 << 22);
   u3m_pave(c3y);
 }
 
diff --git a/pkg/urbit/tests/hashtable_tests.c b/pkg/urbit/tests/hashtable_tests.c
index 6322a331cc..3b36dc8876 100644
--- a/pkg/urbit/tests/hashtable_tests.c
+++ b/pkg/urbit/tests/hashtable_tests.c
@@ -9,7 +9,7 @@ c3_w _ch_skip_slot(c3_w mug_w, c3_w lef_w);
 static void
 _setup(void)
 {
-  u3m_init();
+  u3m_init(1 << 26);
   u3m_pave(c3y);
 }
 
diff --git a/pkg/urbit/tests/jam_tests.c b/pkg/urbit/tests/jam_tests.c
index eebc27fc1f..38e1494edc 100644
--- a/pkg/urbit/tests/jam_tests.c
+++ b/pkg/urbit/tests/jam_tests.c
@@ -6,7 +6,7 @@
 static void
 _setup(void)
 {
-  u3m_init();
+  u3m_init(1 << 23);
   u3m_pave(c3y);
 }
 
diff --git a/pkg/urbit/tests/jet_tests.c b/pkg/urbit/tests/jet_tests.c
index 2e96f2305f..4904a959da 100644
--- a/pkg/urbit/tests/jet_tests.c
+++ b/pkg/urbit/tests/jet_tests.c
@@ -5,7 +5,7 @@
 static void
 _setup(void)
 {
-  u3m_init();
+  u3m_init(1 << 20);
   u3m_pave(c3y);
 }
 
diff --git a/pkg/urbit/tests/mug_tests.c b/pkg/urbit/tests/mug_tests.c
index 7ac9783d26..ffd0516747 100644
--- a/pkg/urbit/tests/mug_tests.c
+++ b/pkg/urbit/tests/mug_tests.c
@@ -5,7 +5,7 @@
 static void
 _setup(void)
 {
-  u3m_init();
+  u3m_init(1 << 20);
   u3m_pave(c3y);
 }
 
diff --git a/pkg/urbit/tests/newt_tests.c b/pkg/urbit/tests/newt_tests.c
index 043151784b..6fdbdb759e 100644
--- a/pkg/urbit/tests/newt_tests.c
+++ b/pkg/urbit/tests/newt_tests.c
@@ -6,7 +6,7 @@
 static void
 _setup(void)
 {
-  u3m_init();
+  u3m_init(1 << 20);
   u3m_pave(c3y);
 }
 
diff --git a/pkg/urbit/tests/nock_tests.c b/pkg/urbit/tests/nock_tests.c
index 19c7ef200d..a96ed09bd1 100644
--- a/pkg/urbit/tests/nock_tests.c
+++ b/pkg/urbit/tests/nock_tests.c
@@ -5,7 +5,10 @@
 static void
 _setup(void)
 {
-  u3m_init();
+  //  XX at 1<<24, this succeeds on mac, but bail:exit's on linux.
+  //  investigate possible u3n_prog corruption
+  //
+  u3m_init(1 << 25);
   u3m_pave(c3y);
   u3e_init();
 }