diff --git a/async_postgres/pg_types/encoding.nim b/async_postgres/pg_types/encoding.nim
index a1b9407..257868a 100644
--- a/async_postgres/pg_types/encoding.nim
+++ b/async_postgres/pg_types/encoding.nim
@@ -23,6 +23,11 @@ template writeBE64*(buf: var openArray[byte], pos: int, v: int64) =
   buf[pos + 6] = byte((v shr 8) and 0xFF)
   buf[pos + 7] = byte(v and 0xFF)
 
+template writeBytesAt*(dst: var openArray[byte], pos: int, src: openArray[byte]) =
+  ## Copy src bytes into dst starting at pos. No-op when src is empty.
+  if src.len > 0:
+    copyMem(addr dst[pos], addr src[0], src.len)
+
 proc toPgParamInline*(v: int16): PgParamInline =
   result.oid = OidInt2
   result.format = 1
@@ -276,9 +281,8 @@ proc encodeBinaryArray*(elemOid: int32, elements: seq[seq[byte]]): seq[byte] =
   for e in elements:
     result.writeBE32(pos, int32(e.len))
     pos += 4
-    if e.len > 0:
-      copyMem(addr result[pos], addr e[0], e.len)
-      pos += e.len
+    result.writeBytesAt(pos, e)
+    pos += e.len
 
 proc encodeBinaryArray*(elemOid: int32, elements: seq[Option[seq[byte]]]): seq[byte] =
   ## Encode a 1-dimensional binary array that may contain NULL elements.
@@ -315,9 +319,8 @@ proc encodeBinaryArray*(elemOid: int32, elements: seq[Option[seq[byte]]]): seq[b
       let ev = e.get
       result.writeBE32(pos, int32(ev.len))
       pos += 4
-      if ev.len > 0:
-        copyMem(addr result[pos], addr ev[0], ev.len)
-        pos += ev.len
+      result.writeBytesAt(pos, ev)
+      pos += ev.len
 
 proc encodeBinaryArrayEmpty*(elemOid: int32): seq[byte] =
   ## Encode an empty 1-dimensional PostgreSQL binary array.
@@ -975,14 +978,15 @@ proc encodeHstoreBinary*(v: PgHstore): seq[byte] =
     result.writeBE32(pos, int32(k.len))
     pos += 4
     if k.len > 0:
-      copyMem(addr result[pos], addr k[0], k.len)
+      result.writeBytesAt(pos, k.toOpenArrayByte(0, k.high))
       pos += k.len
     if val.isSome:
-      result.writeBE32(pos, int32(val.get.len))
+      let vs = val.get
+      result.writeBE32(pos, int32(vs.len))
       pos += 4
-      if val.get.len > 0:
-        copyMem(addr result[pos], addr val.get[0], val.get.len)
-        pos += val.get.len
+      if vs.len > 0:
+        result.writeBytesAt(pos, vs.toOpenArrayByte(0, vs.high))
+        pos += vs.len
     else:
       result.writeBE32(pos, -1'i32)
       pos += 4
diff --git a/async_postgres/pg_types/ranges.nim b/async_postgres/pg_types/ranges.nim
index 2bf0b1f..3924cc1 100644
--- a/async_postgres/pg_types/ranges.nim
+++ b/async_postgres/pg_types/ranges.nim
@@ -338,18 +338,14 @@ proc encodeRangeBinaryImpl(r: RangeBinaryInput): seq[byte] =
   result[0] = flags
   var pos = 1
   if r.hasLower:
-    let lb = toBE32(int32(r.lowerData.len))
-    copyMem(addr result[pos], addr lb[0], 4)
+    result.writeBE32(pos, int32(r.lowerData.len))
     pos += 4
-    if r.lowerData.len > 0:
-      copyMem(addr result[pos], addr r.lowerData[0], r.lowerData.len)
-      pos += r.lowerData.len
+    result.writeBytesAt(pos, r.lowerData)
+    pos += r.lowerData.len
   if r.hasUpper:
-    let ub = toBE32(int32(r.upperData.len))
-    copyMem(addr result[pos], addr ub[0], 4)
+    result.writeBE32(pos, int32(r.upperData.len))
     pos += 4
-    if r.upperData.len > 0:
-      copyMem(addr result[pos], addr r.upperData[0], r.upperData.len)
+    result.writeBytesAt(pos, r.upperData)
 
 # toPgParam for range types (text format)
 
@@ -734,16 +730,13 @@ proc encodeMultirangeBinaryImpl(rangeData: seq[seq[byte]]): seq[byte] =
   for rd in rangeData:
     size += 4 + rd.len
   result = newSeq[byte](size)
-  let cnt = toBE32(int32(rangeData.len))
-  copyMem(addr result[0], addr cnt[0], 4)
+  result.writeBE32(0, int32(rangeData.len))
   var pos = 4
   for rd in rangeData:
-    let rl = toBE32(int32(rd.len))
-    copyMem(addr result[pos], addr rl[0], 4)
+    result.writeBE32(pos, int32(rd.len))
     pos += 4
-    if rd.len > 0:
-      copyMem(addr result[pos], addr rd[0], rd.len)
-      pos += rd.len
+    result.writeBytesAt(pos, rd)
+    pos += rd.len
 
 # Multirange toPgParam (text format)
 
diff --git a/async_postgres/pg_types/user_types.nim b/async_postgres/pg_types/user_types.nim
index 3f8911f..2feeb28 100644
--- a/async_postgres/pg_types/user_types.nim
+++ b/async_postgres/pg_types/user_types.nim
@@ -1,9 +1,7 @@
 import std/[options, macros, strutils, typetraits]
 
 import ../pg_protocol
-import ./core
-import ./decoding
-import ./accessors
+import core, decoding, encoding, accessors
 
 # User-defined enum type support
 #
@@ -262,25 +260,20 @@ proc encodeBinaryComposite*(
     if f.data.isSome:
       size += f.data.get.len
   result = newSeq[byte](size)
-  let nf = toBE32(int32(fields.len))
-  copyMem(addr result[0], addr nf[0], 4)
+  result.writeBE32(0, int32(fields.len))
   var pos = 4
   for f in fields:
-    let oid = toBE32(f.oid)
-    copyMem(addr result[pos], addr oid[0], 4)
+    result.writeBE32(pos, f.oid)
     pos += 4
     if f.data.isNone:
-      let nl = toBE32(-1'i32)
-      copyMem(addr result[pos], addr nl[0], 4)
+      result.writeBE32(pos, -1'i32)
       pos += 4
     else:
       let data = f.data.get
-      let dl = toBE32(int32(data.len))
-      copyMem(addr result[pos], addr dl[0], 4)
+      result.writeBE32(pos, int32(data.len))
       pos += 4
-      if data.len > 0:
-        copyMem(addr result[pos], addr data[0], data.len)
-        pos += data.len
+      result.writeBytesAt(pos, data)
+      pos += data.len
 
 proc compositeFieldToText(val: string): string =
   ## Escape a composite field value for text format output.