diff --git a/lib/mathlib.cpp b/lib/mathlib.cpp
index e51645297..0cea33314 100644
--- a/lib/mathlib.cpp
+++ b/lib/mathlib.cpp
@@ -225,6 +225,14 @@ std::string MathLib::multiply(const std::string &first, const std::string &secon
     return toString<double>(toDoubleNumber(first) * toDoubleNumber(second));
 }
 
+std::string MathLib::mod(const std::string &first, const std::string &second)
+{
+    if (MathLib::isInt(first) && MathLib::isInt(second)) {
+        return toString<MathLib::bigint>(toLongNumber(first) % toLongNumber(second));
+    }
+    return toString<double>(fmod(toDoubleNumber(first),toDoubleNumber(second)));
+}
+
 std::string MathLib::calculate(const std::string &first, const std::string &second, char action)
 {
     switch (action) {
@@ -240,6 +248,9 @@ std::string MathLib::calculate(const std::string &first, const std::string &seco
     case '/':
         return MathLib::divide(first, second);
 
+    case '%':
+        return MathLib::mod(first, second);
+
     default:
         throw InternalError(0, std::string("Unexpected action '") + action + "' in MathLib::calculate(). Please report this to Cppcheck developers.");
     }
diff --git a/lib/mathlib.h b/lib/mathlib.h
index c92c50659..c584f8d0d 100644
--- a/lib/mathlib.h
+++ b/lib/mathlib.h
@@ -54,6 +54,7 @@ public:
     static std::string subtract(const std::string & first, const std::string & second);
     static std::string multiply(const std::string & first, const std::string & second);
     static std::string divide(const std::string & first, const std::string & second);
+    static std::string mod(const std::string & first, const std::string & second);
     static std::string calculate(const std::string & first, const std::string & second, char action);
 
     static std::string sin(const std::string & tok);
diff --git a/test/testmathlib.cpp b/test/testmathlib.cpp
index 87484e6bb..0536d6d9b 100644
--- a/test/testmathlib.cpp
+++ b/test/testmathlib.cpp
@@ -30,6 +30,7 @@ private:
 
     void run() {
         TEST_CASE(calculate);
+        TEST_CASE(calculate1);
         TEST_CASE(convert);
         TEST_CASE(isint);
         TEST_CASE(isnegative);
@@ -123,6 +124,16 @@ private:
         ASSERT_THROW(MathLib::calculate("1","2",'j'),InternalError);
     }
 
+    void calculate1() { // mod
+        ASSERT_EQUALS("0"    , MathLib::calculate("2"	 , "1"    , '%'));
+        ASSERT_EQUALS("0"    , MathLib::calculate("2.0"  , "1.0"  , '%'));
+        ASSERT_EQUALS("2"    , MathLib::calculate("12"   , "5"   , '%'));
+        ASSERT_EQUALS("1"    , MathLib::calculate("100"  , "3"   , '%'));
+        ASSERT_EQUALS("12"   , MathLib::calculate("12.0" , "13.0" , '%'));
+        ASSERT_EQUALS("1.3"  , MathLib::calculate("5.3"  , "2.0" , '%'));
+        ASSERT_EQUALS("1.7"  , MathLib::calculate("18.5" , "4.2" , '%'));
+    }
+
     void convert() {
         // ------------------
         // tolong conversion:
diff --git a/test/testother.cpp b/test/testother.cpp
index 3615563fc..9c3fdf370 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -108,6 +108,7 @@ private:
         TEST_CASE(testMisusedScopeObjectDoesNotPickNestedClass);
         TEST_CASE(trac2071);
         TEST_CASE(trac2084);
+        TEST_CASE(trac3693);
 
         TEST_CASE(assignmentInAssert);
 
@@ -2387,6 +2388,16 @@ private:
         ASSERT_EQUALS("[trac1132.cpp:16]: (error) instance of \"Lock\" object destroyed immediately\n", errout.str());
     }
 
+    void trac3693() {
+        check("struct A{\n"
+              "  enum {\n"
+              "    b = 300\n"
+              "  };\n"
+              "};\n"
+              "const int DFLT_TIMEOUT = A::b % 1000000 ;\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void testMisusedScopeObjectDoesNotPickFunction1() {
         check("int main ( )\n"
               "{\n"