diff --git a/src/tucucore/montecarlopercentilecalculator.cpp b/src/tucucore/montecarlopercentilecalculator.cpp
index af4ee3fd..6480677b 100644
--- a/src/tucucore/montecarlopercentilecalculator.cpp
+++ b/src/tucucore/montecarlopercentilecalculator.cpp
@@ -26,6 +26,23 @@
 #ifdef TUCU_CONFIG_OPENMP
 #include <omp.h>
 #endif // TUCU_CONFIG_OPENMP
+
+#ifdef __EMSCRIPTEN__
+// WebAssembly build without pthreads: run each worker synchronously in the calling thread.
+namespace {
+struct TucuThread
+{
+    template<class F, class = std::enable_if_t<!std::is_same_v<std::decay_t<F>, TucuThread> > >
+    explicit TucuThread(F&& _f)
+    {
+        _f();
+    }
+    void join() {}
+};
+} // namespace
+#else
+using TucuThread = std::thread;
+#endif
 #include <random>
 #include <thread>
 
@@ -692,18 +709,18 @@ foundFalse:
 #else  // TUCU_SINGLETHREADEDPERCENTILESORTOPTION
 
     // Sort and set percentile
-    for (unsigned int cycle = 0; cycle < recordedIntakes.size(); cycle++) {
-        for (unsigned int point = 0; point < static_cast<unsigned int>(recordedIntakes[cycle].getNbPoints()); point++) {
+    for (unsigned int cycle = 0; cycle < _recordedIntakes.size(); cycle++) {
+        for (unsigned int point = 0; point < static_cast<unsigned int>(_recordedIntakes[cycle].getNbPoints()); point++) {
 
             // Sort concentrations in increasing order at each time (at the cycle and at the point)
             std::sort(
-                    concentrations[cycle][point].begin(),
-                    concentrations[cycle][point].end(),
+                    _concentrations[cycle][point].begin(),
+                    _concentrations[cycle][point].end(),
                     [&](const double v1, const double v2) { return v1 < v2; });
 
             for (unsigned int percRankIdx = 0; percRankIdx < _percentileRanks.size(); percRankIdx++) {
                 int pos = positions[percRankIdx];
-                double conc = concentrations[cycle][point][pos];
+                double conc = _concentrations[cycle][point][pos];
                 _percentiles.appendPercentile(percRankIdx, cycle, point, conc);
             }
         }
@@ -1038,11 +1055,11 @@ ComputingStatus AposterioriMonteCarloPercentileCalculator::calculateEtasAndEpsil
     auto nbSamplePerThread =
             static_cast<unsigned int>(ceil(static_cast<double>(nbInitialSamples) / static_cast<double>(nbThreads)));
 
-    std::vector<std::thread> workers;
+    std::vector<TucuThread> workers;
     std::vector<int> nbZeros(nbThreads, 0);
     for (unsigned thread = 0; thread < nbThreads; thread++) {
 
-        workers.push_back(std::thread([thread,
+        workers.push_back(TucuThread([thread,
                                        &abort,
                                        _aborter,
                                        nbSamplePerThread,
@@ -1132,7 +1149,7 @@ ComputingStatus AposterioriMonteCarloPercentileCalculator::calculateEtasAndEpsil
         }));
     }
 
-    std::for_each(workers.begin(), workers.end(), [](std::thread& _t) { _t.join(); });
+    std::for_each(workers.begin(), workers.end(), [](TucuThread& _t) { _t.join(); });
 
     if (abort) {
         return ComputingStatus::Aborted;