diff --git a/ext/java/org/jruby/ext/digest/CRC32.java b/ext/java/org/jruby/ext/digest/CRC32.java
new file mode 100644
index 0000000..7ac38ee
--- /dev/null
+++ b/ext/java/org/jruby/ext/digest/CRC32.java
@@ -0,0 +1,127 @@
+/*
+ **** BEGIN LICENSE BLOCK *****
+ * BSD 2-Clause License
+ *
+ * Copyright (c) 2026, Olle Jonsson
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ ***** END LICENSE BLOCK *****/
+
+package org.jruby.ext.digest;
+
+import java.io.IOException;
+
+import org.jruby.Ruby;
+import org.jruby.RubyClass;
+import org.jruby.RubyFixnum;
+import org.jruby.RubyModule;
+import org.jruby.RubyObject;
+import org.jruby.RubyString;
+import org.jruby.anno.JRubyClass;
+import org.jruby.anno.JRubyMethod;
+import org.jruby.api.Access;
+import org.jruby.runtime.ThreadContext;
+import org.jruby.runtime.Visibility;
+import org.jruby.runtime.builtin.IRubyObject;
+import org.jruby.runtime.load.Library;
+import org.jruby.util.ByteList;
+
+public class CRC32 implements Library {
+
+    public void load(final Ruby runtime, boolean wrap) throws IOException {
+        runtime.getLoadService().require("digest");
+        ThreadContext context = runtime.getCurrentContext();
+        RubyModule Digest = Access.getModule(context, "Digest");
+        RubyClass Base = Digest.getClass(context, "Base");
+        RubyClass crc32 = Digest.defineClassUnder(context, "CRC32", Base, DigestCRC32::new);
+        crc32.defineMethods(context, DigestCRC32.class);
+    }
+
+    private static final class CloneableCRC32 extends java.util.zip.CRC32 implements Cloneable {
+        @Override
+        public CloneableCRC32 clone() throws CloneNotSupportedException {
+            return (CloneableCRC32) super.clone();
+        }
+    }
+
+    @JRubyClass(name="Digest::CRC32", parent="Digest::Base")
+    public static class DigestCRC32 extends RubyObject {
+        private static final long serialVersionUID = -2811470471354871234L;
+
+        private transient CloneableCRC32 crc = new CloneableCRC32();
+
+        public DigestCRC32(Ruby runtime, RubyClass type) {
+            super(runtime, type);
+        }
+
+        @JRubyMethod(required = 1, visibility = Visibility.PRIVATE)
+        @Override
+        public IRubyObject initialize_copy(ThreadContext context, IRubyObject obj) {
+            if (this == obj) return this;
+            DigestCRC32 from = (DigestCRC32) obj;
+            this.checkFrozen();
+            try {
+                this.crc = from.crc.clone();
+            } catch (CloneNotSupportedException e) {
+                throw getRuntime().newRaiseException(getRuntime().getTypeError(), "Could not initialize copy of Digest::CRC32");
+            }
+            return this;
+        }
+
+        @JRubyMethod(name = {"update", "<<"}, required = 1)
+        public IRubyObject update(IRubyObject obj) {
+            ByteList bytes = obj.convertToString().getByteList();
+            crc.update(bytes.getUnsafeBytes(), bytes.getBegin(), bytes.getRealSize());
+            return this;
+        }
+
+        @JRubyMethod()
+        public IRubyObject finish() {
+            long val = crc.getValue();
+            crc.reset();
+            byte[] digest = new byte[] {
+                (byte)(val >>> 24),
+                (byte)(val >>> 16),
+                (byte)(val >>> 8),
+                (byte) val
+            };
+            return RubyString.newStringNoCopy(getRuntime(), digest);
+        }
+
+        @JRubyMethod()
+        public IRubyObject reset() {
+            crc.reset();
+            return this;
+        }
+
+        @JRubyMethod()
+        public IRubyObject digest_length() {
+            return RubyFixnum.newFixnum(getRuntime(), 4);
+        }
+
+        @JRubyMethod()
+        public IRubyObject block_length() {
+            return RubyFixnum.newFixnum(getRuntime(), 8);
+        }
+    }
+}
diff --git a/ext/java/org/jruby/ext/digest/lib/digest/crc32.rb b/ext/java/org/jruby/ext/digest/lib/digest/crc32.rb
new file mode 100644
index 0000000..186cea2
--- /dev/null
+++ b/ext/java/org/jruby/ext/digest/lib/digest/crc32.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+require "digest.jar"
+JRuby::Util.load_ext("org.jruby.ext.digest.CRC32")
diff --git a/test/digest/test_digest.rb b/test/digest/test_digest.rb
index 95cce93..8a39a7b 100644
--- a/test/digest/test_digest.rb
+++ b/test/digest/test_digest.rb
@@ -204,7 +204,80 @@ class TestCRC32 < Test::Unit::TestCase
       Data1 => "352441c2",
       Data2 => "171a3f5f",
     }
-  end if defined?(Digest::CRC32)
+
+    def test_digest_byte_order
+      # CRC32("abc") = 0x352441C2; raw digest bytes must be big-endian (MSB first)
+      assert_equal [0x35, 0x24, 0x41, 0xC2], Digest::CRC32.digest("abc").bytes
+    end
+
+    def test_digest_length
+      assert_equal 4, Digest::CRC32.new.digest_length
+    end
+
+    def test_block_length
+      assert_equal 8, Digest::CRC32.new.block_length
+    end
+
+    def test_empty_string
+      assert_equal "00000000", Digest::CRC32.hexdigest("")
+    end
+
+    def test_single_null_byte
+      assert_equal "d202ef8d", Digest::CRC32.hexdigest("\x00".b)
+    end
+
+    def test_high_bytes
+      # Exercises the unsigned byte masking (& 0xFF) in the update loop
+      assert_equal "08eaaf6d", Digest::CRC32.hexdigest("\xFF\xFE\xFD".b)
+    end
+
+    def test_all_byte_values
+      # Exercises every entry in the lookup table
+      assert_equal "29058c73", Digest::CRC32.hexdigest((0..255).map(&:chr).join.b)
+    end
+
+    def test_incremental_equals_one_shot
+      inc = Digest::CRC32.new
+      inc << "a" << "b" << "c"
+      assert_equal "352441c2", inc.hexdigest
+    end
+
+    def test_clone_mid_stream_independence
+      d = Digest::CRC32.new
+      d << "ab"
+      copy = d.clone
+      d << "c"
+      copy << "c"
+      assert_equal d.hexdigest, copy.hexdigest
+    end
+
+    def test_reset
+      d = Digest::CRC32.new
+      d << "abc"
+      d.reset
+      d << "abc"
+      assert_equal "352441c2", d.hexdigest
+    end
+
+    def test_digest_is_non_destructive
+      d = Digest::CRC32.new
+      d << "abc"
+      assert_equal d.hexdigest, d.hexdigest
+    end
+
+    def test_digest_bang_resets_state
+      d = Digest::CRC32.new
+      d << "abc"
+      d.hexdigest!
+      assert_equal "00000000", d.hexdigest
+    end
+
+    def test_initialize_copy_into_frozen_raises
+      dest = Digest::CRC32.allocate
+      dest.freeze
+      assert_raise(FrozenError) { dest.send(:initialize_copy, Digest::CRC32.new) }
+    end
+  end
 
   class TestBase < Test::Unit::TestCase
     def test_base