diff --git a/src/kits/support/BufferedDataIO.cpp b/src/kits/support/BufferedDataIO.cpp
index 7fb3c8f017..1978004d90 100644
--- a/src/kits/support/BufferedDataIO.cpp
+++ b/src/kits/support/BufferedDataIO.cpp
@@ -95,10 +95,10 @@ BBufferedDataIO::Flush()
 	} else if (bytesWritten >= 0) {
 		fSize -= bytesWritten;
 		fPosition += bytesWritten;
-		return B_ERROR;
+		return B_PARTIAL_WRITE;
 	}
 
-	return bytesWritten;
+	return B_OK;
 }
 
 
@@ -172,6 +172,15 @@ BBufferedDataIO::Write(const void* buffer, size_t size)
 
 	TRACE("%p::Write(size %lu)\n", this, size);
 
+	if (size > fBufferSize || fBuffer == NULL) {
+		// request is larger than our buffer, just fill it directly
+		status_t status = Flush();
+		if (status != B_OK)
+			return status;
+
+		return fStream.Write(buffer, size);
+	}
+
 	if (!fDirty) {
 		// Throw away a read-only buffer if necessary
 		TRACE("%p: throw away previous buffer.\n", this);
@@ -180,39 +189,21 @@ BBufferedDataIO::Write(const void* buffer, size_t size)
 	}
 
 	size_t bytesWritten = 0;
-
-	if (size > fBufferSize || fBuffer == NULL) {
-		// request is larger than our buffer, just fill it directly
-		bytesWritten = fSize;
-
-		status_t status = Flush();
-		if (status != B_OK)
-			return status;
-
-		ssize_t streamWritten = fStream.Write(buffer, size);
-		if (streamWritten >= 0)
-			return bytesWritten + streamWritten;
-
-		return streamWritten;
-	}
-
-	bytesWritten = min_c(size, fBufferSize - fSize - fPosition);
-	TRACE("%p: write %" B_PRIuSIZE " bytes to the buffer.\n", this,
-		bytesWritten);
-	memcpy(fBuffer + fPosition + fSize, buffer, bytesWritten);
-	fSize += bytesWritten;
-	size -= bytesWritten;
-
-	if (size > 0) {
-		status_t status = Flush();
-		if (status != B_OK)
-			return status;
-
-		memcpy(fBuffer, (uint8*)buffer + bytesWritten, size);
-		fPosition = 0;
-		fSize = size;
+	while (size > 0) {
+		size_t toCopy = min_c(size, fBufferSize - (fPosition + fSize));
+		TRACE("%p: write %" B_PRIuSIZE " bytes to the buffer.\n", this,
+			toCopy);
+		memcpy(fBuffer + (fPosition + fSize), buffer, toCopy);
+		fSize += toCopy;
+		bytesWritten += toCopy;
+		size -= toCopy;
 		fDirty = true;
-		bytesWritten += size;
+
+		if ((fPosition + fSize) == fBufferSize) {
+			status_t status = Flush();
+			if (status != B_OK)
+				return bytesWritten;
+		}
 	}
 
 	return bytesWritten;
diff --git a/src/tests/kits/storage/DataIOTest.cpp b/src/tests/kits/storage/DataIOTest.cpp
new file mode 100644
index 0000000000..ae8a63ecb3
--- /dev/null
+++ b/src/tests/kits/storage/DataIOTest.cpp
@@ -0,0 +1,46 @@
+// DataIOTest.cpp
+
+#include <string.h>
+#include <BufferedDataIO.h>
+
+#include <TestShell.h>
+
+#include "DataIOTest.h"
+
+
+CppUnit::Test*
+DataIOTest::Suite() {
+	CppUnit::TestSuite *suite = new CppUnit::TestSuite();
+	typedef CppUnit::TestCaller<DataIOTest> TC;
+
+	suite->addTest(new TC("BResourceString::BufferedDataIO Test",
+		&DataIOTest::BufferedDataIOTest));
+
+	return suite;
+}
+
+
+void
+DataIOTest::BufferedDataIOTest()
+{
+	// very basic test
+	NextSubTest();
+	{
+		BMallocIO mallocIO;
+		CPPUNIT_ASSERT(mallocIO.SetSize(1024) == B_OK);
+
+		BBufferedDataIO bufferedDataIO(mallocIO, 8, false);
+		CPPUNIT_ASSERT(bufferedDataIO.InitCheck() == B_OK);
+
+		CPPUNIT_ASSERT(bufferedDataIO.Write("test ", 5) == 5);
+		CPPUNIT_ASSERT(bufferedDataIO.Write("test ", 5) == 5);
+		CPPUNIT_ASSERT(bufferedDataIO.Write("test ", 5) == 5);
+
+		CPPUNIT_ASSERT(bufferedDataIO.Flush() == B_OK);
+
+		CPPUNIT_ASSERT(bufferedDataIO.Write("longer-test", 12) == 12);
+
+		CPPUNIT_ASSERT(mallocIO.Position() == 27);
+		CPPUNIT_ASSERT(memcmp(mallocIO.Buffer(), "test test test longer-test", 27) == 0);
+	}
+}
diff --git a/src/tests/kits/storage/DataIOTest.h b/src/tests/kits/storage/DataIOTest.h
new file mode 100644
index 0000000000..235baec492
--- /dev/null
+++ b/src/tests/kits/storage/DataIOTest.h
@@ -0,0 +1,23 @@
+// DataIOTest.h
+
+#ifndef __sk_data_io_test_h__
+#define __sk_data_io_test_h__
+
+#include <cppunit/TestCaller.h>
+#include <cppunit/TestSuite.h>
+
+#include <StorageDefs.h>
+#include <SupportDefs.h>
+
+#include "BasicTest.h"
+
+class DataIOTest : public BasicTest
+{
+public:
+	static CppUnit::Test* Suite();
+
+	void BufferedDataIOTest();
+};
+
+
+#endif	// __sk_data_io_test_h__
diff --git a/src/tests/kits/storage/Jamfile b/src/tests/kits/storage/Jamfile
index b2d0d09fc1..59a146f5e6 100644
--- a/src/tests/kits/storage/Jamfile
+++ b/src/tests/kits/storage/Jamfile
@@ -8,6 +8,7 @@ UnitTestLib libstoragetest.so
 	: StorageKitTestAddon.cpp
 		AppFileInfoTest.cpp
 		BasicTest.cpp
+		DataIOTest.cpp
 		DirectoryTest.cpp
 		EntryTest.cpp
 		FindDirectoryTest.cpp
diff --git a/src/tests/kits/storage/StorageKitTestAddon.cpp b/src/tests/kits/storage/StorageKitTestAddon.cpp
index 17f9417707..4cc8bbe0e3 100644
--- a/src/tests/kits/storage/StorageKitTestAddon.cpp
+++ b/src/tests/kits/storage/StorageKitTestAddon.cpp
@@ -4,6 +4,7 @@
 // ##### Include headers for your tests here #####
 #include "AppFileInfoTest.h"
 #include "DirectoryTest.h"
+#include "DataIOTest.h"
 #include "EntryTest.h"
 #include "FileTest.h"
 #include "FindDirectoryTest.h"
@@ -24,6 +25,7 @@ BTestSuite* getTestSuite() {
 	// ##### Add test suites here #####
 	suite->addTest("BAppFileInfo", AppFileInfoTest::Suite());
 	suite->addTest("BDirectory", DirectoryTest::Suite());
+	suite->addTest("BDataIO", DataIOTest::Suite());
 	suite->addTest("BEntry", EntryTest::Suite());
 	suite->addTest("BFile", FileTest::Suite());
 #if 0