diff --git a/httplib.h b/httplib.h
index fa34904..fb922e7 100644
--- a/httplib.h
+++ b/httplib.h
@@ -50,7 +50,9 @@
 
 #ifndef CPPHTTPLIB_THREAD_POOL_COUNT
 #define CPPHTTPLIB_THREAD_POOL_COUNT                                           \
-  ((std::max)(8u, std::thread::hardware_concurrency() - 1))
+  ((std::max)(8u, std::thread::hardware_concurrency() > 0                      \
+                      ? std::thread::hardware_concurrency() - 1                \
+                      : 0))
 #endif
 
 /*