diff --git a/lib/checkbufferoverrun.cpp b/lib/checkbufferoverrun.cpp
index 896ab7ffe..bca5b523f 100644
--- a/lib/checkbufferoverrun.cpp
+++ b/lib/checkbufferoverrun.cpp
@@ -577,15 +577,20 @@ void CheckBufferOverrun::checkFunctionParameter(const Token &tok, unsigned int p
     }
 
     else if (par == 2) {
-        total_size["read"] = 3;
-        total_size["pread"] = 3;
-        total_size["write"] = 3;
-        total_size["recv"] = 3;
-        total_size["recvfrom"] = 3;
-        total_size["send"] = 3;
-        total_size["sendto"] = 3;
+        if (_settings->standards.posix) {
+            total_size["read"] = 3;
+            total_size["pread"] = 3;
+            total_size["write"] = 3;
+            total_size["recv"] = 3;
+            total_size["recvfrom"] = 3;
+            total_size["send"] = 3;
+            total_size["sendto"] = 3;
+        }
     }
 
+    if (Token::Match(tok.previous(), ".") || Token::Match(tok.tokAt(-2), "!!std ::"))
+        total_size.clear();
+
     std::map<std::string, unsigned int>::const_iterator it = total_size.find(tok.str());
     if (it != total_size.end()) {
         if (arrayInfo.element_size() == 0)
diff --git a/test/testbufferoverrun.cpp b/test/testbufferoverrun.cpp
index aafce26f5..ea4658062 100644
--- a/test/testbufferoverrun.cpp
+++ b/test/testbufferoverrun.cpp
@@ -2162,6 +2162,15 @@ private:
               "sendto(s, str, 4, 0, 0x0, 0x0);\n"
               "}");
         ASSERT_EQUALS("[test.cpp:4]: (error) Buffer is accessed out of bounds: str\n", errout.str());
+
+        // #4968 - not standard function
+        check("void f() {\n"
+              "    char str[3];\n"
+              "    foo.memset(str, 0, 100);\n"
+              "    foo::memset(str, 0, 100);\n"
+              "    std::memset(str, 0, 100);\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:5]: (error) Buffer is accessed out of bounds: str\n", errout.str());
     }