diff --git a/devtools/CaptureEG.cpp b/devtools/CaptureEG.cpp
index 558b0d14..b5313254 100644
--- a/devtools/CaptureEG.cpp
+++ b/devtools/CaptureEG.cpp
@@ -284,6 +284,7 @@ void Application::performSfzUpdate()
 
     QString code;
     code += "<region>\n";
+    code += "key=69\n";
     code += "sample="; code += QFileInfo(samplePath).fileName(); code += "\n";
     code += _ui->envelopeEdit->toPlainText();
 
diff --git a/src/sfizz/ADSREnvelope.cpp b/src/sfizz/ADSREnvelope.cpp
index 9581ab7a..bb86115b 100644
--- a/src/sfizz/ADSREnvelope.cpp
+++ b/src/sfizz/ADSREnvelope.cpp
@@ -40,11 +40,9 @@ void ADSREnvelope<Type>::reset(const EGDescription& desc, const Region& region,
 
     releaseDelay = 0;
     shouldRelease = false;
-    freeRunning = (
-        (region.trigger == SfzTrigger::release)
+    freeRunning = ((region.trigger == SfzTrigger::release)
         || (region.trigger == SfzTrigger::release_key)
-        || region.loopMode == SfzLoopMode::one_shot
-    );
+        || (region.loopMode == SfzLoopMode::one_shot && (region.isGenerator() || region.oscillator)));
     currentValue = this->start;
     currentState = State::Delay;
 }
@@ -117,8 +115,7 @@ void ADSREnvelope<Type>::getBlock(absl::Span<Type> output) noexcept
             // release takes effect this frame
             currentState = State::Release;
             releaseDelay = -1;
-        }
-        else if (shouldRelease && releaseDelay > 0) {
+        } else if (shouldRelease && releaseDelay > 0) {
             // prevent computing the segment further than release point
             size = std::min<size_t>(size, releaseDelay);
         }
@@ -188,6 +185,8 @@ void ADSREnvelope<Type>::getBlock(absl::Span<Type> output) noexcept
     this->currentValue = currentValue;
     this->shouldRelease = shouldRelease;
     this->releaseDelay = releaseDelay;
+
+    ASSERT(!hasNanInf(output));
 }
 
 template <class Type>
diff --git a/src/sfizz/MathHelpers.h b/src/sfizz/MathHelpers.h
index 960ccb73..9fa734f1 100644
--- a/src/sfizz/MathHelpers.h
+++ b/src/sfizz/MathHelpers.h
@@ -11,6 +11,7 @@
 #pragma once
 #include "Config.h"
 #include "Macros.h"
+#include "absl/types/span.h"
 #include <algorithm>
 #include <cmath>
 #include <random>
@@ -292,3 +293,38 @@ inline F fp_from_parts(bool sgn, int ex, uint64_t mant)
         (static_cast<I>(sgn) << (T::e_bits + T::m_bits));
     return u.real;
 }
+
+template <class F>
+inline bool fp_naninf(F x)
+{
+    typedef FP_traits<F> T;
+    typedef typename T::same_size_int I;
+    union {
+        F real;
+        I integer;
+    } u;
+    u.real = x;
+    const auto all_ones = ((1u << T::e_bits) - 1);
+    const auto ex = (u.integer >> T::m_bits) & all_ones;
+    return ex == all_ones;
+}
+
+template <class Type>
+bool hasNanInf(absl::Span<Type> span)
+{
+    for (const auto& x : span)
+        if (fp_naninf(x))
+            return true;
+
+    return false;
+}
+
+template <class Type>
+bool isValidAudio(absl::Span<Type> span)
+{
+    for (const auto& x : span)
+        if (x < -1.0f || x > 1.0f)
+            return false;
+
+    return true;
+}
diff --git a/src/sfizz/Synth.cpp b/src/sfizz/Synth.cpp
index 1141624c..0870905f 100644
--- a/src/sfizz/Synth.cpp
+++ b/src/sfizz/Synth.cpp
@@ -624,6 +624,11 @@ void sfz::Synth::renderBlock(AudioSpan<float> buffer) noexcept
 
     // Reset the dispatch counter
     dispatchDuration = Duration(0);
+
+    ASSERT(!hasNanInf(buffer.getConstSpan(0)));
+    ASSERT(!hasNanInf(buffer.getConstSpan(1)));
+    ASSERT(isValidAudio(buffer.getConstSpan(0)));
+    ASSERT(isValidAudio(buffer.getConstSpan(1)));
 }
 
 void sfz::Synth::noteOn(int delay, int noteNumber, uint8_t velocity) noexcept
diff --git a/src/sfizz/Voice.cpp b/src/sfizz/Voice.cpp
index 251a1167..fcb1d9fd 100644
--- a/src/sfizz/Voice.cpp
+++ b/src/sfizz/Voice.cpp
@@ -241,6 +241,12 @@ void sfz::Voice::renderBlock(AudioSpan<float> buffer) noexcept
 
     powerHistory.push(buffer.meanSquared());
     this->triggerDelay = absl::nullopt;
+#if 0
+    ASSERT(!hasNanInf(buffer.getConstSpan(0)));
+    ASSERT(!hasNanInf(buffer.getConstSpan(1)));
+    ASSERT(isValidAudio(buffer.getConstSpan(0)));
+    ASSERT(isValidAudio(buffer.getConstSpan(1)));
+#endif
 }
 
 void sfz::Voice::amplitudeEnvelope(absl::Span<float> modulationSpan) noexcept
@@ -515,6 +521,13 @@ void sfz::Voice::fillWithData(AudioSpan<float> buffer) noexcept
 
     sourcePosition = indices->back();
     floatPositionOffset = rightCoeffs->back();
+
+#if 0
+    ASSERT(!hasNanInf(buffer.getConstSpan(0)));
+    ASSERT(!hasNanInf(buffer.getConstSpan(1)));
+    ASSERT(isValidAudio(buffer.getConstSpan(0)));
+    ASSERT(isValidAudio(buffer.getConstSpan(1)));
+#endif
 }
 
 void sfz::Voice::fillWithGenerator(AudioSpan<float> buffer) noexcept
@@ -573,6 +586,13 @@ void sfz::Voice::fillWithGenerator(AudioSpan<float> buffer) noexcept
             }
         }
     }
+
+#if 0
+    ASSERT(!hasNanInf(buffer.getConstSpan(0)));
+    ASSERT(!hasNanInf(buffer.getConstSpan(1)));
+    ASSERT(isValidAudio(buffer.getConstSpan(0)));
+    ASSERT(isValidAudio(buffer.getConstSpan(1)));
+#endif
 }
 
 bool sfz::Voice::checkOffGroup(int delay, uint32_t group) noexcept
diff --git a/src/sfizz/Wavetables.cpp b/src/sfizz/Wavetables.cpp
index b04c0a8c..617d3901 100644
--- a/src/sfizz/Wavetables.cpp
+++ b/src/sfizz/Wavetables.cpp
@@ -253,8 +253,18 @@ WavetableMulti WavetableMulti::createForHarmonicProfile(
 const WavetableMulti* WavetableMulti::getSilenceWavetable()
 {
     static WavetableMulti wm;
-    wm.allocateStorage(1);
-    wm.fillExtra();
+    static bool initialized { false };
+
+    if (!initialized) {
+        constexpr unsigned numTables = WavetableMulti::numTables();
+        wm.allocateStorage(1);
+        for (unsigned m = 0; m < numTables; ++m) {
+            float* ptr = const_cast<float*>(wm.getTablePointer(m));
+            *ptr = 0;
+        }
+        wm.fillExtra();
+        initialized = true;
+    }
     return &wm;
 }
 
diff --git a/tests/FloatHelpersT.cpp b/tests/FloatHelpersT.cpp
index 58b92acc..ecfc0cf0 100644
--- a/tests/FloatHelpersT.cpp
+++ b/tests/FloatHelpersT.cpp
@@ -7,6 +7,7 @@
 #include "catch2/catch.hpp"
 #include "sfizz/MathHelpers.h"
 #include <cmath>
+#include <limits>
 
 TEST_CASE("[FloatMath] Fast ilog2 (float)")
 {
@@ -51,3 +52,19 @@ TEST_CASE("[FloatMath] Break apart and reconstruct (double)")
         REQUIRE(fp_from_parts<double>(sgn, ex, mant.num) == f);
     }
 }
+
+TEST_CASE("[FloatMath] Nan/Inf checker")
+{
+    REQUIRE(fp_naninf(std::numeric_limits<double>::quiet_NaN()));
+    REQUIRE(fp_naninf(std::numeric_limits<float>::quiet_NaN()));
+    REQUIRE(fp_naninf(std::numeric_limits<double>::infinity()));
+    REQUIRE(fp_naninf(std::numeric_limits<float>::infinity()));
+    REQUIRE(fp_naninf(-std::numeric_limits<double>::infinity()));
+    REQUIRE(fp_naninf(-std::numeric_limits<float>::infinity()));
+    REQUIRE(!fp_naninf(0.0f));
+    REQUIRE(!fp_naninf(0.0));
+    REQUIRE(!fp_naninf(1.0f));
+    REQUIRE(!fp_naninf(1.0));
+    REQUIRE(!fp_naninf(-1.0f));
+    REQUIRE(!fp_naninf(-1.0));
+}