diff --git a/src/jsonpak/dollar.nim b/src/jsonpak/dollar.nim
index 2be5c9d..58c8f85 100644
--- a/src/jsonpak/dollar.nim
+++ b/src/jsonpak/dollar.nim
@@ -1,5 +1,29 @@
-from std/json import escapeJsonUnquoted, escapeJson
 import private/[bitabs, jsonnode, jsontree], std/importutils
+from std/strutils import toHex
+
+proc escapeJsonUnquoted*(s: string; result: var string) =
+  ## Converts a string `s` to its JSON representation without quotes.
+  ## Appends to `result`.
+  for c in s:
+    case c
+    of '\L': result.add("\\n")
+    of '\b': result.add("\\b")
+    of '\f': result.add("\\f")
+    of '\t': result.add("\\t")
+    of '\v': result.add("\\u000b")
+    of '\r': result.add("\\r")
+    of '"': result.add("\\\"")
+    of '\0'..'\7': result.add("\\u000" & $ord(c))
+    of '\14'..'\31': result.add("\\u00" & toHex(ord(c), 2))
+    of '\\': result.add("\\\\")
+    else: result.add(c)
+
+proc escapeJson*(s: string; result: var string) =
+  ## Converts a string `s` to its JSON representation with quotes.
+  ## Appends to `result`.
+  result.add("\"")
+  escapeJsonUnquoted(s, result)
+  result.add("\"")
 
 type
   JsonIter = object
diff --git a/src/jsonpak/private/bitabs.nim b/src/jsonpak/private/bitabs.nim
index 36de5ad..adb9983 100644
--- a/src/jsonpak/private/bitabs.nim
+++ b/src/jsonpak/private/bitabs.nim
@@ -2,6 +2,7 @@
 ## of (Table[LitId, Val], Table[Val, LitId]).
 
 import std/[hashes, assertions]
+from std/math import nextPowerOfTwo
 
 const
   defaultInitialSize = 64
@@ -15,6 +16,13 @@ type
     vals: seq[T] # indexed by LitId
     keys: seq[Key] # indexed by hash(val)
 
+proc slotsNeeded(count: Natural): int {.inline.} =
+  # Make sure to synchronize with `mustRehash`
+  result = nextPowerOfTwo(count * 3 div 2 + 4)
+
+proc initBiTable*[T](initialSize = defaultInitialSize): BiTable[T] =
+  BiTable[T](vals: @[], keys: newSeq[Key](slotsNeeded(initialSize)))
+
 proc nextTry(h, maxHash: Hash): Hash {.inline.} =
   result = (h + 1) and maxHash