diff --git a/Mono.Security.Cryptography/CryptoService.cs b/Mono.Security.Cryptography/CryptoService.cs
index 013e0019d..dd9613fe0 100644
--- a/Mono.Security.Cryptography/CryptoService.cs
+++ b/Mono.Security.Cryptography/CryptoService.cs
@@ -146,7 +146,7 @@ public static byte [] ComputeHash (params ByteBuffer [] buffers)
 
 			using (var crypto_stream = new CryptoStream (Stream.Null, sha1, CryptoStreamMode.Write)) {
 				for (int i = 0; i < buffers.Length; i++) {
-					crypto_stream.Write (buffers [0].buffer, 0, buffers [0].length);
+					crypto_stream.Write (buffers [i].buffer, 0, buffers [i].length);
 				}
 			}
 
diff --git a/Test/Mono.Cecil.Tests/PortablePdbTests.cs b/Test/Mono.Cecil.Tests/PortablePdbTests.cs
index 6e1efbc90..e741865fa 100644
--- a/Test/Mono.Cecil.Tests/PortablePdbTests.cs
+++ b/Test/Mono.Cecil.Tests/PortablePdbTests.cs
@@ -683,5 +683,42 @@ public void WriteAndReadAgainModuleWithDeterministicMvid ()
 			using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { SymbolReaderProvider = new PortablePdbReaderProvider () })) {
 			}
 		}
+
+		[Test]
+		public void DoubleWriteAndReadAgainModuleWithDeterministicMvid ()
+		{
+			Guid mvid1_in, mvid1_out, mvid2_in, mvid2_out;
+
+			{
+				const string resource = "foo.dll";
+				string destination = Path.GetTempFileName ();
+
+				using (var module = GetResourceModule (resource, new ReaderParameters {  })) {
+					mvid1_in = module.Mvid;
+					module.Write (destination, new WriterParameters { DeterministicMvid = true });
+				}
+
+				using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { })) {
+					mvid1_out = module.Mvid;
+				}
+			}
+
+			{
+				const string resource = "hello2.exe";
+				string destination = Path.GetTempFileName ();
+
+				using (var module = GetResourceModule (resource, new ReaderParameters {  })) {
+					mvid2_in = module.Mvid;
+					module.Write (destination, new WriterParameters { DeterministicMvid = true });
+				}
+
+				using (var module = ModuleDefinition.ReadModule (destination, new ReaderParameters { })) {
+					mvid2_out = module.Mvid;
+				}
+			}
+
+			Assert.AreNotEqual (mvid1_in, mvid2_in);
+			Assert.AreNotEqual (mvid1_out, mvid2_out);
+		}
 	}
 }
diff --git a/Test/Resources/assemblies/foo.dll b/Test/Resources/assemblies/foo.dll
new file mode 100644
index 000000000..56b17e0d3
Binary files /dev/null and b/Test/Resources/assemblies/foo.dll differ
diff --git a/Test/Resources/assemblies/hello2.exe b/Test/Resources/assemblies/hello2.exe
new file mode 100644
index 000000000..6cc52a912
Binary files /dev/null and b/Test/Resources/assemblies/hello2.exe differ