diff --git a/include/audacity/Types.h b/include/audacity/Types.h
index 1614cc7dd..63f028964 100644
--- a/include/audacity/Types.h
+++ b/include/audacity/Types.h
@@ -70,7 +70,9 @@ public:
    sampleCount ( int v ) : value { v } {}
    sampleCount ( unsigned v ) : value { v } {}
    sampleCount ( long v ) : value { v } {}
-   sampleCount ( unsigned long v ) : value { v } {}
+
+   // unsigned long is 64 bit on some platforms.  Let it narrow.
+   sampleCount ( unsigned long v ) : value ( v ) {}
 
    // Beware implicit conversions from floating point values!
    // Otherwise the meaning of binary operators with sampleCount change
diff --git a/src/Mix.cpp b/src/Mix.cpp
index a16ca05e2..27993a8dd 100644
--- a/src/Mix.cpp
+++ b/src/Mix.cpp
@@ -255,7 +255,7 @@ Mixer::Mixer(const WaveTrackConstArray &inputTracks,
    , mQueueMaxLen{ 65536 }
    , mSampleQueue{ mNumInputTracks, mQueueMaxLen }
 
-   , mNumChannels{ static_cast<size_t>(numOutChannels) }
+   , mNumChannels{ numOutChannels }
    , mGains{ mNumChannels }
 
    , mMayThrow{ mayThrow }