diff --git a/src/caf_reader.c b/src/caf_reader.c
index 05b2151..2b9950a 100644
--- a/src/caf_reader.c
+++ b/src/caf_reader.c
@@ -75,8 +75,10 @@ int caf_desc(caf_reader_t *reader, int64_t chunk_size)
     ENSURE(mFormatID == M4AF_FOURCC('l','p','c','m'));
     ENSURE(mSampleRate && mBytesPerPacket &&
            mChannelsPerFrame >= 1 && mChannelsPerFrame <= 8 &&
-           mBitsPerChannel && mFramesPerPacket == 1 &&
+           mBitsPerChannel > 0 && mBitsPerChannel < 256 &&
+           mFramesPerPacket == 1 &&
            mBytesPerPacket % mChannelsPerFrame == 0 &&
+           mBytesPerPacket < 256 &&
            mBytesPerPacket >= mChannelsPerFrame * ((mBitsPerChannel + 7) / 8));
 
     desc->sample_rate        = mSampleRate;
diff --git a/src/wav_reader.c b/src/wav_reader.c
index 4c6cc66..638a625 100644
--- a/src/wav_reader.c
+++ b/src/wav_reader.c
@@ -113,8 +113,10 @@ int wav_fmt(wav_reader_t *reader, uint32_t size)
     wValidBitsPerSample = wBitsPerSample;
 
     ENSURE(wFormatTag == 1 || wFormatTag == 3 || wFormatTag == 0xfffe);
-    ENSURE(nChannels && nSamplesPerSec && nAvgBytesPerSec &&
-           nBlockAlign && wBitsPerSample && !(wBitsPerSample & 7) &&
+    ENSURE(nChannels > 0 && nChannels <= 8 &&
+           nSamplesPerSec && nAvgBytesPerSec &&
+           nBlockAlign && nBlockAlign < 256 &&
+           wBitsPerSample && wBitsPerSample < 256 && !(wBitsPerSample & 7) &&
            nBlockAlign == nChannels * wBitsPerSample / 8);
 
     if (wFormatTag == 3)