diff --git a/test/test_pcm_channels.cxx b/test/test_pcm_channels.cxx
index a36fb39f3..748a76351 100644
--- a/test/test_pcm_channels.cxx
+++ b/test/test_pcm_channels.cxx
@@ -27,7 +27,7 @@
 void
 PcmChannelsTest::TestChannels16()
 {
-	constexpr size_t N = 256;
+	constexpr size_t N = 509;
 	const auto src = TestDataBuffer<int16_t, N * 2>();
 
 	PcmBuffer buffer;
@@ -55,7 +55,7 @@ PcmChannelsTest::TestChannels16()
 void
 PcmChannelsTest::TestChannels32()
 {
-	constexpr size_t N = 256;
+	constexpr size_t N = 509;
 	const auto src = TestDataBuffer<int32_t, N * 2>();
 
 	PcmBuffer buffer;
diff --git a/test/test_pcm_dither.cxx b/test/test_pcm_dither.cxx
index 6751d94fe..09a2b5cf9 100644
--- a/test/test_pcm_dither.cxx
+++ b/test/test_pcm_dither.cxx
@@ -24,7 +24,7 @@
 void
 PcmDitherTest::TestDither24()
 {
-	constexpr unsigned N = 256;
+	constexpr unsigned N = 509;
 	const auto src = TestDataBuffer<int32_t, N>(RandomInt24());
 
 	int16_t dest[N];
@@ -40,7 +40,7 @@ PcmDitherTest::TestDither24()
 void
 PcmDitherTest::TestDither32()
 {
-	constexpr unsigned N = 256;
+	constexpr unsigned N = 509;
 	const auto src = TestDataBuffer<int32_t, N>();
 
 	int16_t dest[N];
diff --git a/test/test_pcm_format.cxx b/test/test_pcm_format.cxx
index 381554921..825a8bd84 100644
--- a/test/test_pcm_format.cxx
+++ b/test/test_pcm_format.cxx
@@ -29,7 +29,7 @@
 void
 PcmFormatTest::TestFormat8to16()
 {
-	constexpr size_t N = 256;
+	constexpr size_t N = 509;
 	const auto src = TestDataBuffer<int8_t, N>();
 
 	PcmBuffer buffer;
@@ -45,7 +45,7 @@ PcmFormatTest::TestFormat8to16()
 void
 PcmFormatTest::TestFormat16to24()
 {
-	constexpr size_t N = 256;
+	constexpr size_t N = 509;
 	const auto src = TestDataBuffer<int16_t, N>();
 
 	PcmBuffer buffer;
@@ -60,7 +60,7 @@ PcmFormatTest::TestFormat16to24()
 void
 PcmFormatTest::TestFormat16to32()
 {
-	constexpr size_t N = 256;
+	constexpr size_t N = 509;
 	const auto src = TestDataBuffer<int16_t, N>();
 
 	PcmBuffer buffer;
@@ -75,7 +75,7 @@ PcmFormatTest::TestFormat16to32()
 void
 PcmFormatTest::TestFormatFloat()
 {
-	constexpr size_t N = 256;
+	constexpr size_t N = 509;
 	const auto src = TestDataBuffer<int16_t, N>();
 
 	PcmBuffer buffer1, buffer2;
diff --git a/test/test_pcm_mix.cxx b/test/test_pcm_mix.cxx
index 65d009050..973b58f4d 100644
--- a/test/test_pcm_mix.cxx
+++ b/test/test_pcm_mix.cxx
@@ -27,7 +27,7 @@ template<typename T, SampleFormat format, typename G=RandomInt<T>>
 static void
 TestPcmMix(G g=G())
 {
-	constexpr unsigned N = 256;
+	constexpr unsigned N = 509;
 	const auto src1 = TestDataBuffer<T, N>(g);
 	const auto src2 = TestDataBuffer<T, N>(g);
 
diff --git a/test/test_pcm_pack.cxx b/test/test_pcm_pack.cxx
index 161e13145..fff3e10f0 100644
--- a/test/test_pcm_pack.cxx
+++ b/test/test_pcm_pack.cxx
@@ -25,7 +25,7 @@
 void
 PcmPackTest::TestPack24()
 {
-	constexpr unsigned N = 256;
+	constexpr unsigned N = 509;
 	const auto src = TestDataBuffer<int32_t, N>(RandomInt24());
 
 	uint8_t dest[N * 3];
@@ -49,7 +49,7 @@ PcmPackTest::TestPack24()
 void
 PcmPackTest::TestUnpack24()
 {
-	constexpr unsigned N = 256;
+	constexpr unsigned N = 509;
 	const auto src = TestDataBuffer<uint8_t, N * 3>();
 
 	int32_t dest[N];
diff --git a/test/test_pcm_volume.cxx b/test/test_pcm_volume.cxx
index de880563d..2d908f6c1 100644
--- a/test/test_pcm_volume.cxx
+++ b/test/test_pcm_volume.cxx
@@ -39,7 +39,7 @@ TestVolume(G g=G())
 	PcmVolume pv;
 	CPPUNIT_ASSERT(pv.Open(F, IgnoreError()));
 
-	constexpr size_t N = 256;
+	constexpr size_t N = 509;
 	static value_type zero[N];
 	const auto _src = TestDataBuffer<value_type, N>(g);
 	const ConstBuffer<void> src(_src, sizeof(_src));
@@ -98,7 +98,7 @@ PcmVolumeTest::TestVolumeFloat()
 	PcmVolume pv;
 	CPPUNIT_ASSERT(pv.Open(SampleFormat::FLOAT, IgnoreError()));
 
-	constexpr size_t N = 256;
+	constexpr size_t N = 509;
 	static float zero[N];
 	const auto _src = TestDataBuffer<float, N>(RandomFloat());
 	const ConstBuffer<void> src(_src, sizeof(_src));