diff --git a/Source/BlepOsc.h b/Source/BlepOsc.h
index 4f3d894..807f063 100644
--- a/Source/BlepOsc.h
+++ b/Source/BlepOsc.h
@@ -6,10 +6,24 @@ enum class BlepWave : int { Sine = 0, Saw, Square, Triangle };
 class BlepOsc
 {
 public:
-    void prepare (double sampleRate) { sr = sampleRate; resetPhase(); }
+    void prepare (double sampleRate)
+    {
+        sr = juce::jmax (1.0, sampleRate);
+        setFrequency ((float) freq);
+        resetPhase();
+    }
     void setWave (BlepWave w) { wave = w; }
-    void setFrequency (float f) { freq = juce::jmax (0.0f, f); inc = freq / (float) sr; }
-    void resetPhase (float p = 0.0f) { phase = juce::jlimit (0.0f, 1.0f, p); }
+    void setFrequency (float f)
+    {
+        const float nyquist = 0.5f * (float) sr;
+        freq = juce::jlimit (0.0f, juce::jmax (0.0f, nyquist), f);
+        inc = freq / (float) sr;
+    }
+    void resetPhase (float p = 0.0f)
+    {
+        phase = juce::jlimit (0.0f, 1.0f, p);
+        z1 = 0.0f;
+    }
 
     inline float process()
     {