diff --git a/lib/ulid/constants.rb b/lib/ulid/constants.rb
index 79d8d25..a3cda16 100644
--- a/lib/ulid/constants.rb
+++ b/lib/ulid/constants.rb
@@ -24,7 +24,7 @@ module Constants
     # B32_CROCKFORD_CHARS = "0123456789ABCDEFGHJKMNPQRSTVWXYZ"
     # B32_RCF4648_CHARS = "0123456789ABCDEFGHIJKLMNOPQRSTUV"
 
-    B32_CROCKFORD_FRAGMENT = "JKMNPQRSTVWXYZ".upcase.freeze
-    B32_RCF4648_FRAGMENT = "IJKLMNOPQRSTUV".downcase.freeze # forcing downcase becase .to_s(32) is always lowercase
+    B32_CROCKFORD_FRAGMENT = "JKMNPQRSTVWXYZ"
+    B32_RCF4648_FRAGMENT = "ijklmnopqrstuv" # downcase because .to_s(32) is always lowercase
   end
 end
diff --git a/lib/ulid/generate.rb b/lib/ulid/generate.rb
index 5f6c979..ca93a9a 100644
--- a/lib/ulid/generate.rb
+++ b/lib/ulid/generate.rb
@@ -9,15 +9,18 @@ module Generate
 
     # returns the binary ULID as Base32 encoded string.
     def encode32
-      (hi, lo) = bytes.unpack("Q>Q>")
-      value = (hi << 64) | lo
+      high = bytes.unpack1("Q>")
+      low = bytes.unpack1("@8Q>")
+      value = (high << 64) | low
 
       # use the RFC4648 Base32 encoding and convert to Crockford's Base32 with a simple translate
       # assumes that the value is a 128-bit integer
       # also assumes that .to_s(32) is lowercase
-      b32 = value.to_s(32).tr!(B32_RCF4648_FRAGMENT, B32_CROCKFORD_FRAGMENT).upcase!
+      b32 = value.to_s(32)
+      b32.tr!(B32_RCF4648_FRAGMENT, B32_CROCKFORD_FRAGMENT)
+      b32.upcase!
 
-      return "0" + b32 if b32.length == 25
+      return "0#{b32}" if b32.length == 25
 
       b32
     end
diff --git a/lib/ulid/parse.rb b/lib/ulid/parse.rb
index dc3a189..8727e51 100644
--- a/lib/ulid/parse.rb
+++ b/lib/ulid/parse.rb
@@ -22,7 +22,7 @@ def decode10(input)
     end
 
     def unpack_ulid_bytes(packed_bytes)
-      time_int, _ = ("\x00\x00" + packed_bytes).unpack("Q>")
+      time_int = ("\x00\x00#{packed_bytes}").unpack1("Q>")
       seed = packed_bytes[6..-1]
 
       [Time.at(time_int.to_f / 1000.0), seed]
diff --git a/lib/ulid/version.rb b/lib/ulid/version.rb
index 664393e..553b42c 100644
--- a/lib/ulid/version.rb
+++ b/lib/ulid/version.rb
@@ -1,4 +1,3 @@
 module ULID
-  VERSION = "1.0.3"
+  VERSION = "1.0.4"
 end
-