diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index 547b997d0..fc6c41e27 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -157,7 +157,16 @@ bool isSameExpression(const Token *tok1, const Token *tok2, const std::set<std::
 
 static bool isOppositeCond(const Token * const cond1, const Token * const cond2, const std::set<std::string> &constFunctions)
 {
-    if (!cond1 || !cond1->isComparisonOp() || !cond2 || !cond2->isComparisonOp())
+    if (!cond1 || !cond2)
+        return false;
+
+    if (cond1->str() == "!")
+        return isSameExpression(cond1->astOperand1(), cond2, constFunctions);
+
+    if (cond2->str() == "!")
+        return isSameExpression(cond1, cond2->astOperand1(), constFunctions);
+
+    if (!cond1->isComparisonOp() || !cond2->isComparisonOp())
         return false;
 
     const std::string &comp1 = cond1->str();
@@ -1260,7 +1269,16 @@ void CheckOther::checkIncorrectLogicOperator()
         const Scope * scope = symbolDatabase->functionScopes[ii];
 
         for (const Token* tok = scope->classStart->next(); tok != scope->classEnd; tok = tok->next()) {
-            if (Token::Match(tok, "&&|%oror%")) {
+            // Opposite comparisons
+            if (Token::Match(tok, "%oror%|&&") &&
+                (tok->astOperand1()->isName() || tok->astOperand2()->isName()) &&
+                isOppositeCond(tok->astOperand1(), tok->astOperand2(), _settings->library.functionpure)) {
+
+                const bool alwaysTrue(tok->str() == "||");
+                incorrectLogicOperatorError(tok, tok->expressionString(), alwaysTrue);
+            }
+
+            else if (Token::Match(tok, "&&|%oror%")) {
                 // Comparison #1 (LHS)
                 const Token *comp1 = tok->astOperand1();
                 if (comp1 && comp1->str() == tok->str())
diff --git a/test/testother.cpp b/test/testother.cpp
index 5d0f9b23e..dbd74ea7a 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -134,6 +134,7 @@ private:
         TEST_CASE(incorrectLogicOperator4);
         TEST_CASE(incorrectLogicOperator5); // complex expressions
         TEST_CASE(incorrectLogicOperator6); // char literals
+        TEST_CASE(incorrectLogicOperator7); // opposite expressions: (expr || !expr)
         TEST_CASE(secondAlwaysTrueFalseWhenFirstTrueError);
         TEST_CASE(incorrectLogicOp_condSwapping);
 
@@ -4199,6 +4200,13 @@ private:
         TODO_ASSERT_EQUALS("error", "", errout.str());
     }
 
+    void incorrectLogicOperator7() { // opposite expressions
+        check("void f(int i) {\n"
+              "  if (i || !i) {}\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:2]: (warning) Logical disjunction always evaluates to true: i||!i.\n", errout.str());
+    }
+
     void secondAlwaysTrueFalseWhenFirstTrueError() {
         check("void f(int x) {\n"
               "    if (x > 5 && x != 1)\n"