diff --git a/src/protocol/protocol.jl b/src/protocol/protocol.jl
index f7721d90..cbb27bd1 100644
--- a/src/protocol/protocol.jl
+++ b/src/protocol/protocol.jl
@@ -16,6 +16,7 @@
 ### Code:
 
 include("structs.jl")
+include("validate.jl")
 include("parser.jl")
 include("payload.jl")
 include("headers.jl")
diff --git a/src/protocol/show.jl b/src/protocol/show.jl
index 6eb9cd1b..287ae221 100644
--- a/src/protocol/show.jl
+++ b/src/protocol/show.jl
@@ -91,7 +91,7 @@ function show(io::IO, ::MIME_PROTOCOL, connect::Connect)
 end
 
 function show(io::IO, ::MIME_PROTOCOL, pub::Pub)
-    hbytes = length(pub.headers)
+    hbytes = pub.headers_length
     nbytes = length(pub.payload)
     if hbytes > 0
         write(io, "H")
@@ -105,8 +105,7 @@ function show(io::IO, ::MIME_PROTOCOL, pub::Pub)
     if hbytes > 0
         write(io, " $hbytes")
     end
-    write(io, " $(hbytes + nbytes)\r\n")
-    write(io, pub.headers)
+    write(io, " $(nbytes)\r\n")
     write(io, pub.payload)
     write(io, "\r\n")
 end
diff --git a/src/protocol/structs.jl b/src/protocol/structs.jl
index 5a2024d8..d8ca4229 100644
--- a/src/protocol/structs.jl
+++ b/src/protocol/structs.jl
@@ -127,9 +127,9 @@ struct Pub <: ProtocolMessage
     subject::String
     "The reply subject that subscribers can use to send a response back to the publisher/requestor."
     reply_to::Union{String, Nothing}
-    "Header version `NATS/1.0␍␊` followed by one or more `name: value` pairs, each separated by `␍␊`."
-    headers::Vector{UInt8}
-    "The message payload data."
+    "Length of headers data inside payload"
+    headers_length::Int64
+    "Optional headers (`NATS/1.0␍␊` followed by one or more `name: value` pairs, each separated by `␍␊`) followed by payload data."
     payload::Vector{UInt8}
 end
 
@@ -173,9 +173,9 @@ struct Msg <: ProtocolMessage
     sid::String
     "The subject on which the publisher is listening for responses."
     reply_to::Union{String, Nothing}
-    "Header version `NATS/1.0␍␊` followed by one or more `name: value` pairs, each separated by `␍␊`."
+    "Length of headers data inside payload"
     headers_length::Int64
-    "The message payload data."
+    "Optional headers (`NATS/1.0␍␊` followed by one or more `name: value` pairs, each separated by `␍␊`) followed by payload data."
     payload::AbstractVector{UInt8}
 end
 
diff --git a/src/protocol/validate.jl b/src/protocol/validate.jl
new file mode 100644
index 00000000..4ad36d76
--- /dev/null
+++ b/src/protocol/validate.jl
@@ -0,0 +1,28 @@
+### validate.jl
+#
+# Copyright (C) 2024 Jakub Wronowski.
+#
+# Maintainer: Jakub Wronowski <jakubwro@users.noreply.github.com>
+# Keywords: nats, nats-client, julia
+#
+# This file is a part of NATS.jl.
+#
+# License is MIT.
+#
+### Commentary:
+#
+# This file contains implementation of functions for validation of protocol messages.
+#
+### Code:
+
+function validate(pub::Pub)
+    isempty(pub.subject) && error("Publication subject is empty")
+    startswith(pub.subject, '.') && error("Publication subject '$(pub.subject)' cannot start with '.'")
+    endswith(pub.subject, '.') && error("Publication subject '$(pub.subject)' cannot end with '.'")
+    for c in pub.subject
+        if c == ' '
+            error("Publication subject contains invalid character '$c'.")
+        end
+    end
+    true
+end
diff --git a/src/pubsub/publish.jl b/src/pubsub/publish.jl
index 29ceb2a0..6fc66e7b 100644
--- a/src/pubsub/publish.jl
+++ b/src/pubsub/publish.jl
@@ -15,6 +15,9 @@
 #
 ### Code:
 
+const mime_payload = MIME_PAYLOAD()
+const mime_headers = MIME_HEADERS()
+
 """
 $(SIGNATURES)
 
@@ -38,9 +41,14 @@ function publish(
     data = nothing;
     reply_to::Union{String, Nothing} = nothing
 )
-    payload_bytes = repr(MIME_PAYLOAD(), data)
-    headers_bytes = repr(MIME_HEADERS(), data)
-    send(connection, Pub(subject, reply_to, headers_bytes, payload_bytes))
+    payload_io = IOBuffer()
+    show(payload_io, mime_headers, data)
+    headers_length = payload_io.size
+    show(payload_io, mime_payload, data)
+    payload_bytes = take!(payload_io)
+    pub = Pub(subject, reply_to, headers_length, payload_bytes)
+    validate(pub)
+    send(connection, pub)
     inc_stats(:msgs_published, 1, connection.stats, state.stats)
     sub_stats = ScopedValues.get(scoped_subscription_stats)
     if !isnothing(sub_stats)
diff --git a/test/benchmarks.jl b/test/benchmarks.jl
index 594c2a16..02198529 100644
--- a/test/benchmarks.jl
+++ b/test/benchmarks.jl
@@ -45,7 +45,7 @@ function msgs_per_second(connection::NATS.Connection, connection2::NATS.Connecti
             Threads.atomic_add!(msgs_after_timeout, 1)
         end
     end
-    pub = NATS.Pub(subject, nothing, UInt8[], uint8_vec("Hi!"))
+    pub = NATS.Pub(subject, nothing, 0, uint8_vec("Hi!"))
     t = Threads.@spawn :default begin
         @time while isopen(tm)
             if time_first_pub == 0.0
@@ -128,8 +128,6 @@ end
 @testset "Publisher benchmark." begin
     connection = NATS.connect()
 
-    # pub = NATS.Pub("zxc", nothing, UInt8[], uint8_vec("Hello world!!!!!"))
-
     tm = Timer(1.0)
     counter = 0
     c = 0
diff --git a/test/connection.jl b/test/connection.jl
index 0c54f15b..bc30b72b 100644
--- a/test/connection.jl
+++ b/test/connection.jl
@@ -241,7 +241,7 @@ NATS.status()
     sleep(0.1)
     @test_throws ErrorException publish(connection, "test_publish_on_drained")
 
-    pub = NATS.Pub("test_publish_on_drained", nothing, UInt8[], UInt8[])
+    pub = NATS.Pub("test_publish_on_drained", nothing, 0, UInt8[])
     @test_throws ErrorException NATS.send(connection, repeat([pub], 10))
 end
 
diff --git a/test/protocol.jl b/test/protocol.jl
index a9e0eb3d..a03b487d 100644
--- a/test/protocol.jl
+++ b/test/protocol.jl
@@ -87,15 +87,15 @@ end
     json = """{"verbose":false,"pedantic":false,"tls_required":false,"lang":"julia","version":"0.0.1"}"""
     @test serialize(JSON3.read(json, NATS.Connect)) == """CONNECT $json\r\n"""
 
-    @test serialize(Pub("FOO", nothing, UInt8[], uint8_vec("Hello NATS!"))) == "PUB FOO 11\r\nHello NATS!\r\n"
-    @test serialize(Pub("FRONT.DOOR", "JOKE.22", UInt8[], uint8_vec("Knock Knock"))) == "PUB FRONT.DOOR JOKE.22 11\r\nKnock Knock\r\n"
-    @test serialize(Pub("NOTIFY", nothing, UInt8[], UInt8[])) == "PUB NOTIFY 0\r\n\r\n"
+    @test serialize(Pub("FOO", nothing, 0, uint8_vec("Hello NATS!"))) == "PUB FOO 11\r\nHello NATS!\r\n"
+    @test serialize(Pub("FRONT.DOOR", "JOKE.22", 0, uint8_vec("Knock Knock"))) == "PUB FRONT.DOOR JOKE.22 11\r\nKnock Knock\r\n"
+    @test serialize(Pub("NOTIFY", nothing, 0, UInt8[])) == "PUB NOTIFY 0\r\n\r\n"
 
-    @test serialize(Pub("FOO", nothing, uint8_vec("NATS/1.0\r\nBar: Baz\r\n\r\n"), uint8_vec("Hello NATS!"))) == "HPUB FOO 22 33\r\nNATS/1.0\r\nBar: Baz\r\n\r\nHello NATS!\r\n"
-    @test serialize(Pub("FRONT.DOOR", "JOKE.22", uint8_vec("NATS/1.0\r\nBREAKFAST: donut\r\nLUNCH: burger\r\n\r\n"), uint8_vec("Knock Knock"))) == "HPUB FRONT.DOOR JOKE.22 45 56\r\nNATS/1.0\r\nBREAKFAST: donut\r\nLUNCH: burger\r\n\r\nKnock Knock\r\n"
+    @test serialize(Pub("FOO", nothing, 22, uint8_vec("NATS/1.0\r\nBar: Baz\r\n\r\nHello NATS!"))) == "HPUB FOO 22 33\r\nNATS/1.0\r\nBar: Baz\r\n\r\nHello NATS!\r\n"
+    @test serialize(Pub("FRONT.DOOR", "JOKE.22", 45, uint8_vec("NATS/1.0\r\nBREAKFAST: donut\r\nLUNCH: burger\r\n\r\nKnock Knock"))) == "HPUB FRONT.DOOR JOKE.22 45 56\r\nNATS/1.0\r\nBREAKFAST: donut\r\nLUNCH: burger\r\n\r\nKnock Knock\r\n"
 
-    @test serialize(Pub("NOTIFY", nothing, uint8_vec("NATS/1.0\r\nBar: Baz\r\n\r\n"), UInt8[])) == "HPUB NOTIFY 22 22\r\nNATS/1.0\r\nBar: Baz\r\n\r\n\r\n"
-    @test serialize(Pub("MORNING.MENU", nothing, uint8_vec("NATS/1.0\r\nBREAKFAST: donut\r\nBREAKFAST: eggs\r\n\r\n"), uint8_vec("Yum!"))) == "HPUB MORNING.MENU 47 51\r\nNATS/1.0\r\nBREAKFAST: donut\r\nBREAKFAST: eggs\r\n\r\nYum!\r\n"
+    @test serialize(Pub("NOTIFY", nothing, 22, uint8_vec("NATS/1.0\r\nBar: Baz\r\n\r\n"))) == "HPUB NOTIFY 22 22\r\nNATS/1.0\r\nBar: Baz\r\n\r\n\r\n"
+    @test serialize(Pub("MORNING.MENU", nothing, 47, uint8_vec("NATS/1.0\r\nBREAKFAST: donut\r\nBREAKFAST: eggs\r\n\r\nYum!"))) == "HPUB MORNING.MENU 47 51\r\nNATS/1.0\r\nBREAKFAST: donut\r\nBREAKFAST: eggs\r\n\r\nYum!\r\n"
 
     @test serialize(Sub("FOO", nothing, "1")) == "SUB FOO 1\r\n"
     @test serialize(Sub("BAR", "G1", "44")) == "SUB BAR G1 44\r\n"