diff --git a/CHANGELOG.md b/CHANGELOG.md
index 136ed23f3..1f9e0a73c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@ Added:
 
 - Add PG::Connection#embed_params and keyword `:typename` for its parameter casting. [#726](https://github.com/ged/ruby-pg/pull/726)
   This allows to generate SQL strings with embedded parameters for easier debugging.
-- Add PG:Connection#full_protocol_version which is new in PostgreSQL-18 [#695](https://github.com/ged/ruby-pg/pull/695)
+- Add PG::Connection#full_protocol_version which is new in PostgreSQL-18 [#695](https://github.com/ged/ruby-pg/pull/695)
 - Add PG::Result#each_tuple [#675](https://github.com/ged/ruby-pg/pull/675)
 - Add PG::TypeMap#query_param_encoders to retrieve encoders. [#726](https://github.com/ged/ruby-pg/pull/726)
 - Deduplicate result field name strings for better performance. [#750](https://github.com/ged/ruby-pg/pull/750)
diff --git a/ext/extconf.rb b/ext/extconf.rb
index a2f26886a..cabaa924a 100644
--- a/ext/extconf.rb
+++ b/ext/extconf.rb
@@ -304,8 +304,9 @@ module PG
 end
 
 have_func 'PQencryptPasswordConn', 'libpq-fe.h' or # since PostgreSQL-10
-	abort "Your PostgreSQL is too old. Either install an older version " +
-	      "of this gem or upgrade your database to at least PostgreSQL-10."
+	abort "Your PostgreSQL client library (libpq) is too old. " +
+				"Either install an older version of this gem " +
+				"or upgrade your database to at least PostgreSQL-10."
 # optional headers/functions
 have_func 'PQresultMemorySize', 'libpq-fe.h' # since PostgreSQL-12
 have_func 'timegm'
diff --git a/ext/pg.c b/ext/pg.c
index e6e4ef1ac..0c615581d 100644
--- a/ext/pg.c
+++ b/ext/pg.c
@@ -384,14 +384,10 @@ Init_pg_ext(void)
 	rb_define_const(rb_mPGconstants, "CONNECTION_SSL_STARTUP", INT2FIX(CONNECTION_SSL_STARTUP));
 	/* Internal state - PG.connect() needed. */
 	rb_define_const(rb_mPGconstants, "CONNECTION_NEEDED", INT2FIX(CONNECTION_NEEDED));
-#if PG_MAJORVERSION_NUM >= 10
-	/* Checking if session is read-write. Available since PostgreSQL-10. */
+	/* Checking if session is read-write. */
 	rb_define_const(rb_mPGconstants, "CONNECTION_CHECK_WRITABLE", INT2FIX(CONNECTION_CHECK_WRITABLE));
-#endif
-#if PG_MAJORVERSION_NUM >= 10
-	/* Consuming any extra messages. Available since PostgreSQL-10. */
+	/* Consuming any extra messages. */
 	rb_define_const(rb_mPGconstants, "CONNECTION_CONSUME", INT2FIX(CONNECTION_CONSUME));
-#endif
 #if PG_MAJORVERSION_NUM >= 12
 	/* Negotiating GSSAPI. Available since PostgreSQL-12. */
 	rb_define_const(rb_mPGconstants, "CONNECTION_GSS_STARTUP", INT2FIX(CONNECTION_GSS_STARTUP));
diff --git a/ext/pg_connection.c b/ext/pg_connection.c
index abc2ceaab..8b8ec7bed 100644
--- a/ext/pg_connection.c
+++ b/ext/pg_connection.c
@@ -887,6 +887,8 @@ pgconn_protocol_version(VALUE self)
  * The 3.0 protocol is supported by PostgreSQL server versions 7.4 and above.
  *
  * PG::ConnectionBad is raised if the connection is bad.
+ *
+ * Available since PostgreSQL-18.
  */
 static VALUE
 pgconn_full_protocol_version(VALUE self)
diff --git a/lib/pg/connection.rb b/lib/pg/connection.rb
index c65a7632c..064111752 100644
--- a/lib/pg/connection.rb
+++ b/lib/pg/connection.rb
@@ -551,33 +551,30 @@ def pipeline_sync(*args)
 		alias async_pipeline_sync pipeline_sync
 	end
 
-	if method_defined? :sync_encrypt_password
-		# call-seq:
-		#    conn.encrypt_password( password, username, algorithm=nil ) -> String
-		#
-		# This function is intended to be used by client applications that wish to send commands like <tt>ALTER USER joe PASSWORD 'pwd'</tt>.
-		# It is good practice not to send the original cleartext password in such a command, because it might be exposed in command logs, activity displays, and so on.
-		# Instead, use this function to convert the password to encrypted form before it is sent.
-		#
-		# The +password+ and +username+ arguments are the cleartext password, and the SQL name of the user it is for.
-		# +algorithm+ specifies the encryption algorithm to use to encrypt the password.
-		# Currently supported algorithms are +md5+ and +scram-sha-256+ (+on+ and +off+ are also accepted as aliases for +md5+, for compatibility with older server versions).
-		# Note that support for +scram-sha-256+ was introduced in PostgreSQL version 10, and will not work correctly with older server versions.
-		# If algorithm is omitted or +nil+, this function will query the server for the current value of the +password_encryption+ setting.
-		# That can block, and will fail if the current transaction is aborted, or if the connection is busy executing another query.
-		# If you wish to use the default algorithm for the server but want to avoid blocking, query +password_encryption+ yourself before calling #encrypt_password, and pass that value as the algorithm.
-		#
-		# Return value is the encrypted password.
-		# The caller can assume the string doesn't contain any special characters that would require escaping.
-		#
-		# Available since PostgreSQL-10.
-		# See also corresponding {libpq function}[https://www.postgresql.org/docs/current/libpq-misc.html#LIBPQ-PQENCRYPTPASSWORDCONN].
-		def encrypt_password( password, username, algorithm=nil )
-			algorithm ||= exec("SHOW password_encryption").getvalue(0,0)
-			sync_encrypt_password(password, username, algorithm)
-		end
-		alias async_encrypt_password encrypt_password
+	# call-seq:
+	#    conn.encrypt_password( password, username, algorithm=nil ) -> String
+	#
+	# This function is intended to be used by client applications that wish to send commands like <tt>ALTER USER joe PASSWORD 'pwd'</tt>.
+	# It is good practice not to send the original cleartext password in such a command, because it might be exposed in command logs, activity displays, and so on.
+	# Instead, use this function to convert the password to encrypted form before it is sent.
+	#
+	# The +password+ and +username+ arguments are the cleartext password, and the SQL name of the user it is for.
+	# +algorithm+ specifies the encryption algorithm to use to encrypt the password.
+	# Currently supported algorithms are +md5+ and +scram-sha-256+ (+on+ and +off+ are also accepted as aliases for +md5+, for compatibility with older server versions).
+	# Note that support for +scram-sha-256+ was introduced in PostgreSQL version 10, and will not work correctly with older server versions.
+	# If algorithm is omitted or +nil+, this function will query the server for the current value of the +password_encryption+ setting.
+	# That can block, and will fail if the current transaction is aborted, or if the connection is busy executing another query.
+	# If you wish to use the default algorithm for the server but want to avoid blocking, query +password_encryption+ yourself before calling #encrypt_password, and pass that value as the algorithm.
+	#
+	# Return value is the encrypted password.
+	# The caller can assume the string doesn't contain any special characters that would require escaping.
+	#
+	# See also corresponding {libpq function}[https://www.postgresql.org/docs/current/libpq-misc.html#LIBPQ-PQENCRYPTPASSWORDCONN].
+	def encrypt_password( password, username, algorithm=nil )
+		algorithm ||= exec("SHOW password_encryption").getvalue(0,0)
+		sync_encrypt_password(password, username, algorithm)
 	end
+	alias async_encrypt_password encrypt_password
 
 	# call-seq:
 	#   conn.reset()
@@ -971,7 +968,6 @@ def new(*args)
 
 		# Resolve DNS in Ruby to avoid blocking state while connecting.
 		# Multiple comma-separated values are generated, if the hostname resolves to both IPv4 and IPv6 addresses.
-		# This requires PostgreSQL-10+, so no DNS resolving is done on earlier versions.
 		private def resolve_hosts(iopts)
 			ihosts = iopts[:host].split(",", -1)
 			iports = iopts[:port].split(",", -1)
@@ -1027,8 +1023,8 @@ def new(*args)
 				# So, pass params through and let libpq resolve the service, possibly blocking the Thread.scheduler.
 				# This ensures the processing order of libpq which is:
 				# connection string => service file => environment variable => compiled default
-			elsif iopts_with_defaults[:host] && !iopts_with_defaults[:host].empty? && PG.library_version >= 100000
-				# Do host resolution to avoid blocking Thread.scheduler while DNS queries.
+			elsif iopts_with_defaults[:host] && !iopts_with_defaults[:host].empty?
+				# Do host resolution in Ruby to avoid blocking Thread.scheduler while DNS queries in libpq.
 				iopts_for_reset = iopts_with_defaults
 				iopts = resolve_hosts(iopts_with_defaults)
 			else
diff --git a/spec/pg/connection_spec.rb b/spec/pg/connection_spec.rb
index 0f9b60243..2444a6aef 100644
--- a/spec/pg/connection_spec.rb
+++ b/spec/pg/connection_spec.rb
@@ -2848,14 +2848,8 @@ def wait_check_socket(conn)
 		end
 
 		it "shouldn't type map params unless requested" do
-			if @conn.server_version < 100000
-				expect{
-					@conn.exec_params( "SELECT $1", [5] )
-				}.to raise_error(PG::IndeterminateDatatype){|err| expect(err).to have_attributes(connection: @conn) }
-			else
-				# PostgreSQL-10 maps to TEXT type (OID 25)
-				expect( @conn.exec_params( "SELECT $1", [5] ).ftype(0)).to eq(25)
-			end
+			# PostgreSQL maps to TEXT type (OID 25)
+			expect( @conn.exec_params( "SELECT $1", [5] ).ftype(0)).to eq(25)
 		end
 
 		it "should raise an error on invalid encoder to put_copy_data" do