diff --git a/kittens/transfer/algorithm.c b/kittens/transfer/algorithm.c
index 945749147..4a4c4ec7b 100644
--- a/kittens/transfer/algorithm.c
+++ b/kittens/transfer/algorithm.c
@@ -8,7 +8,6 @@
 
 #include "data-types.h"
 #include "binary.h"
-#include "kitty-uthash.h"
 #include <math.h>
 #include <xxhash.h>
 
@@ -433,12 +432,16 @@ PyTypeObject Patcher_Type = {
 // Differ {{{
 typedef struct Signature { uint64_t index, strong_hash; } Signature;
 
-typedef struct SignatureMap {
-    int weak_hash;
+typedef struct SignatureVal {
     Signature sig, *weak_hash_collisions;
     size_t len, cap;
-    UT_hash_handle hh;
-} SignatureMap;
+} SignatureVal;
+#define NAME SignatureMap
+#define KEY_TY int
+#define VAL_TY SignatureVal
+static void free_signature_val(SignatureVal x) { free(x.weak_hash_collisions); }
+#define VAL_DTOR_FN free_signature_val
+#include "kitty-verstable.h"
 
 typedef struct Differ {
     PyObject_HEAD
@@ -447,7 +450,7 @@ typedef struct Differ {
     Rsync rsync;
     bool signature_header_parsed;
     buffer buf;
-    SignatureMap *signature_map;
+    SignatureMap signature_map;
 
     PyObject *read, *write;
     bool written, finished;
@@ -458,30 +461,21 @@ typedef struct Differ {
 
 static int
 Differ_init(PyObject *s, PyObject *args, PyObject *kwds) {
-    Patcher *self = (Patcher*)s;
+    Differ *self = (Differ*)s;
     static char *kwlist[] = {NULL};
     if (!PyArg_ParseTupleAndKeywords(args, kwds, "", kwlist)) return -1;
     const char *err = init_rsync(&self->rsync, default_block_size, 0, 0);
     if (err != NULL) { PyErr_SetString(RsyncError, err); return -1; }
+    vt_init(&self->signature_map);
     return 0;
 }
 
-static void
-free_sigmap(SignatureMap *map) {
-    SignatureMap *current, *tmp;
-    HASH_ITER(hh, map, current, tmp) {
-        HASH_DEL(map, current);
-        free(current->weak_hash_collisions);
-        free(current);
-    }
-}
-
 static void
 Differ_dealloc(PyObject *self) {
     Differ *p = (Differ*)self;
     if (p->buf.data) free(p->buf.data);
     free_rsync(&p->rsync);
-    if (p->signature_map) free_sigmap(p->signature_map);
+    vt_cleanup(&p->signature_map);
     Py_TYPE(self)->tp_free(self);
 }
 
@@ -510,7 +504,7 @@ parse_signature_header(Differ *self) {
 }
 
 static bool
-add_collision(SignatureMap *sm, Signature s) {
+add_collision(SignatureVal *sm, Signature s) {
     if (sm->cap < sm->len + 1) {
         size_t new_cap = MAX(sm->cap * 2, 8u);
         sm->weak_hash_collisions = realloc(sm->weak_hash_collisions, new_cap * sizeof(sm->weak_hash_collisions[0]));
@@ -525,17 +519,14 @@ static size_t
 parse_signature_block(Differ *self, uint8_t *data, size_t len) {
     if (len < 20) return 0;
     int weak_hash = le32dec(data + 8);
-    SignatureMap *sm = NULL;
-    HASH_FIND_INT(self->signature_map, &weak_hash, sm);
-    if (sm == NULL) {
-        sm = calloc(1, sizeof(SignatureMap));
-        if (sm == NULL) { PyErr_NoMemory(); return 0; }
-        sm->weak_hash = weak_hash;
-        sm->sig.index = le64dec(data);
-        sm->sig.strong_hash = le64dec(data+12);
-        HASH_ADD_INT(self->signature_map, weak_hash, sm);
+    SignatureMap_itr i = vt_get(&self->signature_map, weak_hash);
+    if (vt_is_end(i)) {
+        SignatureVal s = {0};
+        s.sig.index = le64dec(data);
+        s.sig.strong_hash = le64dec(data+12);
+        vt_insert(&self->signature_map, weak_hash, s);
     } else {
-        if (!add_collision(sm, (Signature){.index=le64dec(data), .strong_hash=le64dec(data+12)})) return 0;
+        if (!add_collision(&i.data->val, (Signature){.index=le64dec(data), .strong_hash=le64dec(data+12)})) return 0;
     }
     return 20;
 }
@@ -659,7 +650,7 @@ ensure_idx_valid(Differ *self, size_t idx) {
 }
 
 static bool
-find_strong_hash(SignatureMap *sm, uint64_t q, uint64_t *block_index) {
+find_strong_hash(const SignatureVal *sm, uint64_t q, uint64_t *block_index) {
     if (sm->sig.strong_hash == q) { *block_index = sm->sig.index; return true; }
     for (size_t i = 0; i < sm->len; i++) {
         if (sm->weak_hash_collisions[i].strong_hash == q) { *block_index = sm->weak_hash_collisions[i].index; return true; }
@@ -734,11 +725,10 @@ read_next(Differ *self) {
 		self->window.sz = self->rsync.block_size;
         rolling_checksum_full(&self->rc, self->buf.data + self->window.pos, self->window.sz);
     }
-    SignatureMap *sm = NULL;
     int weak_hash = self->rc.val;
     uint64_t block_index = 0;
-    HASH_FIND_INT(self->signature_map, &weak_hash, sm);
-    if (sm != NULL && find_strong_hash(sm, self->rsync.hasher.oneshot64(self->buf.data + self->window.pos, self->window.sz), &block_index)) {
+    SignatureMap_itr i = vt_get(&self->signature_map, weak_hash);
+    if (!vt_is_end(i) && find_strong_hash(&i.data->val, self->rsync.hasher.oneshot64(self->buf.data + self->window.pos, self->window.sz), &block_index)) {
         if (!send_data(self)) return false;
         if (!enqueue(self, (Operation){.type=OpBlock, .block_index=block_index})) return false;
 		self->window.pos += self->window.sz;