diff --git a/src/mysql/connection.cr b/src/mysql/connection.cr
index bc648d2..9cdf932 100644
--- a/src/mysql/connection.cr
+++ b/src/mysql/connection.cr
@@ -1,6 +1,29 @@
 require "socket"
 
 class MySql::Connection < DB::Connection
+  class ConnectionError < Exception; end
+
+  class UnexpectedPacketError < ConnectionError
+    getter status : UInt8
+
+    def initialize(status)
+      @status = status
+      super("unexpected packet #{status}")
+    end
+  end
+
+  class UnexpectedPacketValueError < ConnectionError
+    getter attribute : String
+    getter value : UInt64
+
+    def initialize(attribute, value)
+      @attribute = attribute
+      @value = value
+
+      super("unexpected value for #{attribute}: #{value}")
+    end
+  end
+
   record Options,
     host : String,
     port : Int32,
@@ -9,7 +32,7 @@ class MySql::Connection < DB::Connection
     initial_catalog : String?,
     charset : String do
     def self.from_uri(uri : URI) : Options
-      host = uri.hostname || raise "no host provided"
+      host = uri.hostname || raise ConnectionError.new("no host provided")
       port = uri.port || 3306
       username = uri.user
       password = uri.password
@@ -44,7 +67,7 @@ class MySql::Connection < DB::Connection
       end
 
       read_ok_or_err do |packet, status|
-        raise "packet #{status} not implemented"
+        raise NotImplementedError.new("packet #{status} not implemented")
       end
     rescue IO::Error
       raise DB::ConnectionRefused.new
@@ -117,13 +140,13 @@ class MySql::Connection < DB::Connection
   # :nodoc:
   def handle_err_packet(packet)
     8.times { packet.read_byte! }
-    raise packet.read_string
+    raise ConnectionError.new(packet.read_string)
   end
 
   # :nodoc:
   def raise_if_err_packet(packet)
     raise_if_err_packet(packet) do |status|
-      raise "unexpected packet #{status}"
+      raise UnexpectedPacketError.new(status)
     end
   end
 
@@ -152,14 +175,14 @@ class MySql::Connection < DB::Connection
         name = packet.read_lenenc_string
         org_name = packet.read_lenenc_string
         next_length = packet.read_lenenc_int # length of fixed-length fields, always 0x0c
-        raise "Unexpected next_length value: #{next_length}." unless next_length == 0x0c
+        raise UnexpectedPacketValueError.new("next_length", next_length) unless next_length == 0x0c
         character_set = packet.read_fixed_int(2).to_u16!
         column_length = packet.read_fixed_int(4).to_u32!
         column_type = packet.read_fixed_int(1).to_u8!
         flags = packet.read_fixed_int(2).to_u16!
         decimal = packet.read_fixed_int(1).to_u8!
         filler = packet.read_fixed_int(2).to_u16! # filler [00] [00]
-        raise "Unexpected filler value #{filler}" unless filler == 0x0000
+        raise UnexpectedPacketValueError.new("filler", filler) unless filler == 0x0000
 
         target << ColumnSpec.new(catalog, schema, table, org_table, name, org_name, character_set, column_length, column_type, flags, decimal)
       end
diff --git a/src/mysql/read_packet.cr b/src/mysql/read_packet.cr
index 56745f4..4151860 100644
--- a/src/mysql/read_packet.cr
+++ b/src/mysql/read_packet.cr
@@ -1,4 +1,8 @@
 class MySql::ReadPacket < IO
+  class EOFError < IO::EOFError; end
+
+  class UnexpectedIntLengthError < Exception; end
+
   @length : Int32 = 0
   @remaining : Int32 = 0
   @seq : UInt8 = 0u8
@@ -32,16 +36,16 @@ class MySql::ReadPacket < IO
 
   {% if compare_versions(Crystal::VERSION, "0.35.0") == 0 %}
     def write(slice) : Int64
-      raise "not implemented"
+      raise NotImplementedError.new("not implemented")
     end
   {% else %}
     def write(slice) : Nil
-      raise "not implemented"
+      raise NotImplementedError.new("not implemented")
     end
   {% end %}
 
   def read_byte!
-    read_byte || raise "Unexpected EOF"
+    read_byte || raise EOFError.new("Unexpected EOF")
   end
 
   def read_string
@@ -88,7 +92,7 @@ class MySql::ReadPacket < IO
           elsif h == 0xfe
             read_bytes(UInt64, IO::ByteFormat::LittleEndian)
           else
-            raise "Unexpected int length"
+            raise UnexpectedIntLengthError.new("Unexpected int length")
           end
 
     res.to_u64
diff --git a/src/mysql/types.cr b/src/mysql/types.cr
index e90548a..c7aa194 100644
--- a/src/mysql/types.cr
+++ b/src/mysql/types.cr
@@ -67,29 +67,29 @@ abstract struct MySql::Type
   end
 
   def self.type_for(t)
-    raise "MySql::Type does not support #{t} values"
+    raise NotImplementedError.new("MySql::Type does not support #{t} values")
   end
 
   def self.db_any_type
-    raise "not implemented"
+    raise NotImplementedError.new("not implemented")
   end
 
   # Writes in packet the value in ProtocolBinary format.
   # Used when sending query params.
   def self.write(packet, v)
-    raise "not supported write"
+    raise NotImplementedError.new("not supported write")
   end
 
   # Reads from packet a value in ProtocolBinary format of the type
   # specified by self.
   def self.read(packet)
-    raise "not supported read"
+    raise NotImplementedError.new("not supported read")
   end
 
   # Parse from str a value in TextProtocol format of the type
   # specified by self.
   def self.parse(str : ::String)
-    raise "not supported"
+    raise NotImplementedError.new("not supported")
   end
 
   # :nodoc:
diff --git a/src/mysql/unprepared_statement.cr b/src/mysql/unprepared_statement.cr
index 5e87a26..587dc23 100644
--- a/src/mysql/unprepared_statement.cr
+++ b/src/mysql/unprepared_statement.cr
@@ -16,7 +16,7 @@ class MySql::UnpreparedStatement < DB::Statement
   end
 
   private def perform_exec_or_query(args : Enumerable)
-    raise "exec/query with args is not supported" if args.size > 0
+    raise NotImplementedError.new("exec/query with args is not supported") if args.size > 0
 
     conn = self.conn
     conn.write_packet do |packet|
diff --git a/src/mysql/write_packet.cr b/src/mysql/write_packet.cr
index e858452..0fa964b 100644
--- a/src/mysql/write_packet.cr
+++ b/src/mysql/write_packet.cr
@@ -3,7 +3,7 @@ class MySql::WritePacket < IO
   end
 
   def read(slice)
-    raise "not implemented"
+    raise NotImplementedError.new("not implemented")
   end
 
   {% if compare_versions(Crystal::VERSION, "0.35.0") == 0 %}