diff --git a/src/pipeline/ExternVocoderStep.cpp b/src/pipeline/ExternVocoderStep.cpp
index 6ec02770..6b1a9bc0 100644
--- a/src/pipeline/ExternVocoderStep.cpp
+++ b/src/pipeline/ExternVocoderStep.cpp
@@ -95,8 +95,6 @@ int ExternVocoderStep::getOutputSampleRate() const
 
 std::shared_ptr<short> ExternVocoderStep::execute(std::shared_ptr<short> inputSamples, int numInputSamples, int* numOutputSamples)
 {
-    const int MAX_OUTPUT_SAMPLES = 1024;
-
     *numOutputSamples = 0;
     short* outputSamples = nullptr;
 
@@ -104,6 +102,12 @@ std::shared_ptr<short> ExternVocoderStep::execute(std::shared_ptr<short> inputSa
     if (numInputSamples > 0)
     {
         codec2_fifo_write(inputSampleFifo_, inputSamples.get(), numInputSamples);
+#ifdef _WIN32
+        // XXX: simulate required processing time as actual I/O is handled
+        // by another thread. For some reason this is only needed on Windows.
+        int timeToSleep = (numInputSamples * 1000 / getInputSampleRate()) >> 2;
+        if (timeToSleep > 0) Sleep(timeToSleep);
+#endif // _WIN32
     }
  
     // Read and return output samples from thread.