diff --git a/simplecpp.cpp b/simplecpp.cpp
index af9a8ce..1dbf026 100755
--- a/simplecpp.cpp
+++ b/simplecpp.cpp
@@ -2617,7 +2617,7 @@ static void simplifySizeof(simplecpp::TokenList &expr, const std::map<std::strin
 static bool isCpp17OrLater(const simplecpp::DUI &dui)
 {
     const std::string std_ver = simplecpp::getCppStdString(dui.std);
-    return !std_ver.empty() && (std_ver >= "201703L");
+    return std_ver.empty() || (std_ver >= "201703L");
 }
 
 static std::string openHeader(std::ifstream &f, const simplecpp::DUI &dui, const std::string &sourcefile, const std::string &header, bool systemheader);
diff --git a/test.cpp b/test.cpp
index d00658a..53beac7 100644
--- a/test.cpp
+++ b/test.cpp
@@ -1373,7 +1373,8 @@ static void has_include_1()
     ASSERT_EQUALS("\n\nA", preprocess(code, dui));
     dui.std = "c++14";
     ASSERT_EQUALS("", preprocess(code, dui));
-    ASSERT_EQUALS("", preprocess(code));
+    // we default to latest standard
+    ASSERT_EQUALS("\n\nA", preprocess(code));
 }
 
 static void has_include_2()
@@ -1388,7 +1389,6 @@ static void has_include_2()
     simplecpp::DUI dui;
     dui.std = "c++17";
     ASSERT_EQUALS("\n\nA", preprocess(code, dui));
-    ASSERT_EQUALS("", preprocess(code));
 }
 
 static void has_include_3()
@@ -1407,7 +1407,6 @@ static void has_include_3()
     // Unless -I is set (preferably, we should differentiate -I and -isystem...)
     dui.includePaths.push_back("./testsuite");
     ASSERT_EQUALS("\n\nA", preprocess(code, dui));
-    ASSERT_EQUALS("", preprocess(code));
 }
 
 static void has_include_4()
@@ -1422,7 +1421,6 @@ static void has_include_4()
     simplecpp::DUI dui;
     dui.std = "c++17";
     ASSERT_EQUALS("\n\nA", preprocess(code, dui));
-    ASSERT_EQUALS("", preprocess(code));
 }
 
 static void has_include_5()
@@ -1437,7 +1435,6 @@ static void has_include_5()
     simplecpp::DUI dui;
     dui.std = "c++17";
     ASSERT_EQUALS("\n\nA", preprocess(code, dui));
-    ASSERT_EQUALS("", preprocess(code));
 }
 
 static void ifdef1()
@@ -2647,6 +2644,7 @@ static void stdcVersionDefine()
     simplecpp::DUI dui;
     dui.std = "c11";
     ASSERT_EQUALS("\n201112L", preprocess(code, dui));
+    ASSERT_EQUALS("\n202311L", preprocess(code)); // default to latest
 }
 
 static void cpluscplusDefine()
@@ -2657,6 +2655,7 @@ static void cpluscplusDefine()
     simplecpp::DUI dui;
     dui.std = "c++11";
     ASSERT_EQUALS("\n201103L", preprocess(code, dui));
+    ASSERT_EQUALS("\n202400L", preprocess(code)); // default to latest
 }
 
 static void invalidStd()