diff --git a/cli/cppcheckexecutor.h b/cli/cppcheckexecutor.h
index 8c26234b9..48cc40bea 100644
--- a/cli/cppcheckexecutor.h
+++ b/cli/cppcheckexecutor.h
@@ -49,7 +49,7 @@ public:
      */
     CppCheckExecutor() = default;
     CppCheckExecutor(const CppCheckExecutor &) = delete;
-    void operator=(const CppCheckExecutor&) = delete;
+    CppCheckExecutor& operator=(const CppCheckExecutor&) = delete;
 
     /**
      * Starts the checking.
diff --git a/cli/executor.h b/cli/executor.h
index a2f377674..a79077794 100644
--- a/cli/executor.h
+++ b/cli/executor.h
@@ -45,7 +45,7 @@ public:
     virtual ~Executor() = default;
 
     Executor(const Executor &) = delete;
-    void operator=(const Executor &) = delete;
+    Executor& operator=(const Executor &) = delete;
 
     virtual unsigned int check() = 0;
 
diff --git a/cli/processexecutor.h b/cli/processexecutor.h
index 0ecde2372..4d3085319 100644
--- a/cli/processexecutor.h
+++ b/cli/processexecutor.h
@@ -43,7 +43,7 @@ class ProcessExecutor : public Executor {
 public:
     ProcessExecutor(const std::list<std::pair<std::string, std::size_t>> &files, const std::list<FileSettings>& fileSettings, const Settings &settings, Suppressions &suppressions, ErrorLogger &errorLogger, CppCheck::ExecuteCmdFn executeCommand);
     ProcessExecutor(const ProcessExecutor &) = delete;
-    void operator=(const ProcessExecutor &) = delete;
+    ProcessExecutor& operator=(const ProcessExecutor &) = delete;
 
     unsigned int check() override;
 
diff --git a/cli/singleexecutor.h b/cli/singleexecutor.h
index 43584c68a..ae8fd9f2d 100644
--- a/cli/singleexecutor.h
+++ b/cli/singleexecutor.h
@@ -37,7 +37,7 @@ class SingleExecutor : public Executor
 public:
     SingleExecutor(CppCheck &cppcheck, const std::list<std::pair<std::string, std::size_t>> &files, const std::list<FileSettings>& fileSettings, const Settings &settings, Suppressions &suppressions, ErrorLogger &errorLogger);
     SingleExecutor(const SingleExecutor &) = delete;
-    void operator=(const SingleExecutor &) = delete;
+    SingleExecutor& operator=(const SingleExecutor &) = delete;
 
     unsigned int check() override;
 
diff --git a/cli/threadexecutor.h b/cli/threadexecutor.h
index 47a6173ad..d1efff729 100644
--- a/cli/threadexecutor.h
+++ b/cli/threadexecutor.h
@@ -45,7 +45,7 @@ class ThreadExecutor : public Executor {
 public:
     ThreadExecutor(const std::list<std::pair<std::string, std::size_t>> &files, const std::list<FileSettings>& fileSettings, const Settings &settings, Suppressions &suppressions, ErrorLogger &errorLogger, CppCheck::ExecuteCmdFn executeCommand);
     ThreadExecutor(const ThreadExecutor &) = delete;
-    void operator=(const ThreadExecutor &) = delete;
+    ThreadExecutor& operator=(const ThreadExecutor &) = delete;
 
     unsigned int check() override;
 
diff --git a/lib/checkmemoryleak.h b/lib/checkmemoryleak.h
index 20309873c..d5a6a5f63 100644
--- a/lib/checkmemoryleak.h
+++ b/lib/checkmemoryleak.h
@@ -86,7 +86,7 @@ private:
 public:
     CheckMemoryLeak() = delete;
     CheckMemoryLeak(const CheckMemoryLeak &) = delete;
-    void operator=(const CheckMemoryLeak &) = delete;
+    CheckMemoryLeak& operator=(const CheckMemoryLeak &) = delete;
 
     CheckMemoryLeak(const Tokenizer *t, ErrorLogger *e, const Settings *s)
         : mTokenizer_(t), mErrorLogger_(e), mSettings_(s) {}