diff --git a/lib/checkfunctions.cpp b/lib/checkfunctions.cpp
index 1432c776a..4d4921bca 100644
--- a/lib/checkfunctions.cpp
+++ b/lib/checkfunctions.cpp
@@ -95,7 +95,11 @@ void CheckFunctions::invalidFunctionUsage()
                     const Token *top = argtok;
                     while (top->astParent() && top->astParent()->str() != "," && top->astParent() != tok->next())
                         top = top->astParent();
-                    if (top->isComparisonOp() || Token::Match(top, "%oror%|&&")) {
+                    const Token *var = top;
+                    while (Token::Match(top, ".|::"))
+                        var = var->astOperand2();
+                    if (Token::Match(top, "%comp%|%oror%|&&|!|true|false") ||
+                        (var && var->variable() && Token::Match(var->variable()->typeStartToken(), "bool"))) {
                         if (_settings->library.isboolargbad(functionToken, argnr))
                             invalidFunctionArgBoolError(top, functionToken->str(), argnr);
 
diff --git a/test/testfunctions.cpp b/test/testfunctions.cpp
index 67659d6cb..ed7aa7967 100644
--- a/test/testfunctions.cpp
+++ b/test/testfunctions.cpp
@@ -404,6 +404,15 @@ private:
         check("int f() { memset(a,b,sizeof(a)!=0); }");
         ASSERT_EQUALS("[test.cpp:1]: (error) Invalid memset() argument nr 3. A non-boolean value is required.\n", errout.str());
 
+        check("int f() { memset(a,b,!c); }");
+        ASSERT_EQUALS("[test.cpp:1]: (error) Invalid memset() argument nr 3. A non-boolean value is required.\n", errout.str());
+
+        // Ticket #6990
+        check("int f(bool c) { memset(a,b,c); }");
+        ASSERT_EQUALS("[test.cpp:1]: (error) Invalid memset() argument nr 3. A non-boolean value is required.\n", errout.str());
+        check("int f() { memset(a,b,true); }");
+        ASSERT_EQUALS("[test.cpp:1]: (error) Invalid memset() argument nr 3. A non-boolean value is required.\n", errout.str());
+
         // Ticket #6588 (c mode)
         check("void record(char* buf, int n) {\n"
               "  memset(buf, 0, n < 255);\n"           /* KO */