diff --git a/lib/checkbufferoverrun.cpp b/lib/checkbufferoverrun.cpp
index 987ab2605..da88c7f37 100644
--- a/lib/checkbufferoverrun.cpp
+++ b/lib/checkbufferoverrun.cpp
@@ -1015,9 +1015,14 @@ void CheckBufferOverrun::checkScope_inner(const Token *tok, const ArrayInfo &arr
             const Token * const sizeArg = args.size() == 3 ? args[2] : nullptr;
             const bool knownSize = sizeArg && sizeArg->hasKnownIntValue();
             const Token * const endToken = tok2->linkAt(1);
+            const bool smallerSrcString = (args.size() == 3 &&
+                                           args[1]->hasKnownValue() &&
+                                           args[1]->values().front().isTokValue() &&
+                                           args[1]->values().front().tokvalue->tokType() == Token::eString &&
+                                           Token::getStrLength(args[1]->values().front().tokvalue) < sizeArg->getKnownIntValue());
 
             // check for strncpy which is not terminated
-            if (knownSize && tok2->str() == "strncpy") {
+            if (knownSize && !smallerSrcString && tok2->str() == "strncpy") {
                 // strncpy takes entire variable length as input size
                 const MathLib::bigint num = sizeArg->getKnownIntValue();
 
@@ -1040,7 +1045,7 @@ void CheckBufferOverrun::checkScope_inner(const Token *tok, const ArrayInfo &arr
             }
 
             // Dangerous usage of strncat..
-            else if (knownSize && tok2->str() == "strncat") {
+            else if (knownSize && !smallerSrcString && tok2->str() == "strncat") {
                 const MathLib::bigint n = sizeArg->getKnownIntValue();
                 if (n >= total_size)
                     strncatUsageError(tok2);
diff --git a/test/testbufferoverrun.cpp b/test/testbufferoverrun.cpp
index 1290471e3..18fb39ac8 100644
--- a/test/testbufferoverrun.cpp
+++ b/test/testbufferoverrun.cpp
@@ -221,6 +221,7 @@ private:
         TEST_CASE(terminateStrncpy1);
         TEST_CASE(terminateStrncpy2);
         TEST_CASE(terminateStrncpy3);
+        TEST_CASE(terminateStrncpy4);
         TEST_CASE(recursive_long_time);
 
         TEST_CASE(crash1);  // Ticket #1587 - crash
@@ -3605,6 +3606,20 @@ private:
         ASSERT_EQUALS("[test.cpp:4]: (warning, inconclusive) The buffer 'str' may not be null-terminated after the call to strncpy().\n", errout.str());
     }
 
+    void terminateStrncpy4() {
+        check("void bar() {\n"
+              "    char buf[4];\n"
+              "    strncpy(buf, \"ab\", 4);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
+        check("void bar() {\n"
+              "    char buf[4];\n"
+              "    strncpy(buf, \"abcde\", 4);\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3]: (warning, inconclusive) The buffer 'buf' is not null-terminated after the call to strncpy().\n", errout.str());
+    }
+
     void recursive_long_time() {
         // Just test that recursive check doesn't take long time
         check("char *f2 ( char *b )\n"