diff --git a/lib/preprocessor.cpp b/lib/preprocessor.cpp
index 33882e53c..749560517 100644
--- a/lib/preprocessor.cpp
+++ b/lib/preprocessor.cpp
@@ -53,8 +53,8 @@ Directive::Directive(const std::string &_file, const int _linenr, const std::str
 {
 }
 
-bool Preprocessor::missingIncludeFlag;
-bool Preprocessor::missingSystemIncludeFlag;
+std::atomic<bool> Preprocessor::missingIncludeFlag;
+std::atomic<bool> Preprocessor::missingSystemIncludeFlag;
 
 char Preprocessor::macroChar = char(1);
 
diff --git a/lib/preprocessor.h b/lib/preprocessor.h
index 8b63a212c..e33dfe9d1 100644
--- a/lib/preprocessor.h
+++ b/lib/preprocessor.h
@@ -23,6 +23,7 @@
 
 #include "config.h"
 
+#include <atomic>
 #include <simplecpp.h>
 #include <istream>
 #include <list>
@@ -84,8 +85,8 @@ public:
     explicit Preprocessor(Settings& settings, ErrorLogger *errorLogger = nullptr);
     virtual ~Preprocessor();
 
-    static bool missingIncludeFlag;
-    static bool missingSystemIncludeFlag;
+    static std::atomic<bool> missingIncludeFlag;
+    static std::atomic<bool> missingSystemIncludeFlag;
 
     void inlineSuppressions(const simplecpp::TokenList &tokens);
 
diff --git a/lib/settings.cpp b/lib/settings.cpp
index cb965ac2b..f291dd923 100644
--- a/lib/settings.cpp
+++ b/lib/settings.cpp
@@ -20,7 +20,7 @@
 
 #include "valueflow.h"
 
-bool Settings::mTerminated;
+std::atomic<bool> Settings::mTerminated;
 
 const char Settings::SafeChecks::XmlRootName[] = "safe-checks";
 const char Settings::SafeChecks::XmlClasses[] = "class-public";
diff --git a/lib/settings.h b/lib/settings.h
index feedf3f68..a4f829b9a 100644
--- a/lib/settings.h
+++ b/lib/settings.h
@@ -30,6 +30,7 @@
 #include "suppressions.h"
 #include "timer.h"
 
+#include <atomic>
 #include <list>
 #include <set>
 #include <string>
@@ -65,7 +66,7 @@ private:
     int mEnabled;
 
     /** @brief terminate checking */
-    static bool mTerminated;
+    static std::atomic<bool> mTerminated;
 
 public:
     Settings();