diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 703cf869..2d0df89c 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -1048,6 +1048,8 @@ make_v:
 
 Value Eval::evaluate(const Position& pos, int* complexity) {
 
+  assert(!pos.checkers());
+
   Value v;
   Value psq = pos.psq_eg_stm();
 
diff --git a/src/search.cpp b/src/search.cpp
index fba9685b..5d54a15d 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -295,10 +295,12 @@ void Thread::search() {
   if (mainThread)
   {
 
-      int rootComplexity;
-      Eval::evaluate(rootPos, &rootComplexity);
-
-      mainThread->complexity = std::min(1.03 + (rootComplexity - 241) / 1552.0, 1.45);
+      if (!rootPos.checkers())
+      {
+          int rootComplexity;
+          Eval::evaluate(rootPos, &rootComplexity);
+          mainThread->complexity = std::min(1.03 + (rootComplexity - 241) / 1552.0, 1.45);
+      }
 
       if (mainThread->bestPreviousScore == VALUE_INFINITE)
           for (int i = 0; i < 4; ++i)
diff --git a/src/thread.cpp b/src/thread.cpp
index c680393e..202768c8 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -160,6 +160,7 @@ void ThreadPool::clear() {
   main()->bestPreviousScore = VALUE_INFINITE;
   main()->bestPreviousAverageScore = VALUE_INFINITE;
   main()->previousTimeReduction = 1.0;
+  main()->complexity = 1.0;
 }