--- a/dom/media/webaudio/blink/DynamicsCompressorKernel.cpp
+++ b/dom/media/webaudio/blink/DynamicsCompressorKernel.cpp
@@ -34,16 +34,17 @@
 
 #include "mozilla/FloatingPoint.h"
 #include "WebAudioUtils.h"
 
 using namespace std;
 
 using namespace mozilla::dom; // for WebAudioUtils
 using mozilla::IsInfinite;
+using mozilla::PositiveInfinity;
 using mozilla::IsNaN;
 using mozilla::MakeUnique;
 
 namespace WebCore {
 
 
 // Metering hits peaks instantly, but releases this fast (in seconds).
 const float meteringReleaseTimeConstant = 0.325f;
@@ -316,17 +317,23 @@ void DynamicsCompressorKernel::process(f
 
         // envelopeRate is the rate we slew from current compressor level to the desired level.
         // The exact rate depends on if we're attacking or releasing and by how much.
         float envelopeRate;
 
         bool isReleasing = scaledDesiredGain > m_compressorGain;
 
         // compressionDiffDb is the difference between current compression level and the desired level.
-        float compressionDiffDb = WebAudioUtils::ConvertLinearToDecibels(m_compressorGain / scaledDesiredGain, -1000.0f);
+        float compressionDiffDb;
+        if (scaledDesiredGain == 0.0) {
+          compressionDiffDb = PositiveInfinity<float>();
+        } else {
+          compressionDiffDb = WebAudioUtils::ConvertLinearToDecibels(m_compressorGain / scaledDesiredGain, -1000.0f);
+        }
+
 
         if (isReleasing) {
             // Release mode - compressionDiffDb should be negative dB
             m_maxAttackCompressionDiffDb = -1;
 
             // Fix gremlins.
             if (IsNaN(compressionDiffDb))
                 compressionDiffDb = -1;