diff --git a/lib/checkunusedvar.cpp b/lib/checkunusedvar.cpp
index 23a71d071..5ef468af7 100644
--- a/lib/checkunusedvar.cpp
+++ b/lib/checkunusedvar.cpp
@@ -93,6 +93,9 @@ public:
         }
 
     private:
+        /** No implementation */
+        ScopeGuard& operator=(const ScopeGuard &);
+
         Variables & _guarded;
         bool _insideLoop;
     };
diff --git a/lib/executionpath.h b/lib/executionpath.h
index e973431f7..359fbde93 100644
--- a/lib/executionpath.h
+++ b/lib/executionpath.h
@@ -35,7 +35,7 @@ class SymbolDatabase;
 class CPPCHECKLIB ExecutionPath {
 private:
     /** No implementation */
-    void operator=(const ExecutionPath &);
+    ExecutionPath& operator=(const ExecutionPath &);
 
 protected:
     Check * const owner;
diff --git a/lib/mathlib.cpp b/lib/mathlib.cpp
index aa0ee2607..240027026 100644
--- a/lib/mathlib.cpp
+++ b/lib/mathlib.cpp
@@ -423,7 +423,6 @@ bool MathLib::isValidSuffix(std::string::const_iterator it, std::string::const_i
             break;
         default:
             return false;
-            break;
         }
     }
     return ((state == SUFFIX_U)   ||