diff --git a/cli/cmdlineparser.cpp b/cli/cmdlineparser.cpp
index 6b9eaac0b6c..de814f05a37 100644
--- a/cli/cmdlineparser.cpp
+++ b/cli/cmdlineparser.cpp
@@ -1257,23 +1257,17 @@ CmdLineParser::Result CmdLineParser::parseFromArgs(int argc, const char* const a
             // --std
             else if (std::strncmp(argv[i], "--std=", 6) == 0) {
                 const std::string std = argv[i] + 6;
+                bool unknown = false;
                 if (std::strncmp(std.c_str(), "c++", 3) == 0) {
-                    const Standards::cppstd_t cppstd = Standards::getCPP(std);
-                    if (cppstd == Standards::CPPInvalid) {
-                        mLogger.printError("unknown --std value '" + std + "'");
-                        return Result::Fail;
-                    }
-                    mSettings.standards.cpp = cppstd;
+                    mSettings.standards.cpp = Standards::getCPP(std, unknown);
                 }
                 else if (std::strncmp(std.c_str(), "c", 1) == 0) {
-                    const Standards::cstd_t cstd = Standards::getC(std);
-                    if (cstd == Standards::CInvalid) {
-                        mLogger.printError("unknown --std value '" + std + "'");
-                        return Result::Fail;
-                    }
-                    mSettings.standards.c = cstd;
+                    mSettings.standards.c = Standards::getC(std, unknown);
                 }
                 else {
+                    unknown = true;
+                }
+                if (unknown) {
                     mLogger.printError("unknown --std value '" + std + "'");
                     return Result::Fail;
                 }
diff --git a/lib/importproject.cpp b/lib/importproject.cpp
index 336e25744c8..31088d80c64 100644
--- a/lib/importproject.cpp
+++ b/lib/importproject.cpp
@@ -268,7 +268,7 @@ static std::string unescape(const std::string &in)
     return out;
 }
 
-void ImportProject::fsParseCommand(FileSettings& fs, const std::string& command)
+bool ImportProject::fsParseCommand(FileSettings& fs, const std::string& command)
 {
     std::string defs;
 
@@ -311,6 +311,13 @@ void ImportProject::fsParseCommand(FileSettings& fs, const std::string& command)
         } else if (F=='s' && startsWith(fval,"td")) {
             ++pos;
             fs.standard = readUntil(command, &pos, " ");
+            bool unknown_std = false;
+            (void)Standards::getCPP(fs.standard, unknown_std);
+            if (unknown_std) (void)Standards::getC(fs.standard, unknown_std);
+            if (unknown_std) {
+                printError("unkown --std value '" + fs.standard + "'");
+                return false;
+            }
         } else if (F == 'i' && fval == "system") {
             ++pos;
             std::string isystem = readUntil(command, &pos, " ");
@@ -339,6 +346,7 @@ void ImportProject::fsParseCommand(FileSettings& fs, const std::string& command)
         }
     }
     fsSetDefines(fs, std::move(defs));
+    return true;
 }
 
 bool ImportProject::importCompileCommands(std::istream &istr)
@@ -416,7 +424,8 @@ bool ImportProject::importCompileCommands(std::istream &istr)
             return false;
         }
         FileSettings fs{std::move(path)};
-        fsParseCommand(fs, command); // read settings; -D, -I, -U, -std, -m*, -f*
+        // read settings; -D, -I, -U, -std, -m*, -f*
+        if (!fsParseCommand(fs, command)) return false;
         std::map<std::string, std::string, cppcheck::stricmp> variables;
         fsSetIncludePaths(fs, directory, fs.includePaths, variables);
         fileSettings.push_back(std::move(fs));
diff --git a/lib/importproject.h b/lib/importproject.h
index 7382b56eb8d..c112a0e068a 100644
--- a/lib/importproject.h
+++ b/lib/importproject.h
@@ -64,7 +64,7 @@ class CPPCHECKLIB WARN_UNUSED ImportProject {
         CPPCHECK_GUI
     };
 
-    static void fsParseCommand(FileSettings& fs, const std::string& command);
+    static bool fsParseCommand(FileSettings& fs, const std::string& command);
     static void fsSetDefines(FileSettings& fs, std::string defs);
     static void fsSetIncludePaths(FileSettings& fs, const std::string &basepath, const std::list<std::string> &in, std::map<std::string, std::string, cppcheck::stricmp> &variables);
 
diff --git a/lib/keywords.cpp b/lib/keywords.cpp
index 8ef2454922f..a26fc5bd786 100644
--- a/lib/keywords.cpp
+++ b/lib/keywords.cpp
@@ -181,8 +181,6 @@ const std::unordered_set<std::string>& Keywords::getAll(Standards::cstd_t cStd)
         return c17_keywords_all;
     case Standards::cstd_t::C23:
         return c23_keywords_all;
-    case Standards::cstd_t::CInvalid:
-        cppcheck::unreachable();
     }
     cppcheck::unreachable();
 }
@@ -205,8 +203,6 @@ const std::unordered_set<std::string>& Keywords::getAll(Standards::cppstd_t cppS
         return cpp23_keywords_all;
     case Standards::cppstd_t::CPP26:
         return cpp26_keywords_all;
-    case Standards::cppstd_t::CPPInvalid:
-        cppcheck::unreachable();
     }
     cppcheck::unreachable();
 }
@@ -226,8 +222,6 @@ const std::unordered_set<std::string>& Keywords::getOnly(Standards::cstd_t cStd)
         return c17_keywords;
     case Standards::cstd_t::C23:
         return c23_keywords;
-    case Standards::cstd_t::CInvalid:
-        cppcheck::unreachable();
     }
     cppcheck::unreachable();
 }
@@ -251,8 +245,6 @@ const std::unordered_set<std::string>& Keywords::getOnly(Standards::cppstd_t cpp
         return cpp23_keywords;
     case Standards::cppstd_t::CPP26:
         return cpp26_keywords;
-    case Standards::cppstd_t::CPPInvalid:
-        cppcheck::unreachable();
     }
     cppcheck::unreachable();
 }
diff --git a/lib/standards.h b/lib/standards.h
index 1efe3ce7056..51f46633e18 100644
--- a/lib/standards.h
+++ b/lib/standards.h
@@ -38,10 +38,10 @@ struct Standards {
     enum Language : std::uint8_t { None, C, CPP };
 
     /** C code standard */
-    enum cstd_t : std::uint8_t { C89, C99, C11, C17, C23, CLatest = C23, CInvalid } c = CLatest;
+    enum cstd_t : std::uint8_t { C89, C99, C11, C17, C23, CLatest = C23 } c = CLatest;
 
     /** C++ code standard */
-    enum cppstd_t : std::uint8_t { CPP03, CPP11, CPP14, CPP17, CPP20, CPP23, CPP26, CPPLatest = CPP26, CPPInvalid } cpp = CPPLatest;
+    enum cppstd_t : std::uint8_t { CPP03, CPP11, CPP14, CPP17, CPP20, CPP23, CPP26, CPPLatest = CPP26 } cpp = CPPLatest;
 
     /** --std value given on command line */
     std::string stdValue;
@@ -64,12 +64,15 @@ struct Standards {
             return "c17";
         case C23:
             return "c23";
-        case CInvalid:
-            return "";
         }
         return "";
     }
     static cstd_t getC(const std::string &std) {
+        bool _unused;
+        return getC(std, _unused);
+    }
+    static cstd_t getC(const std::string &std, bool &unknown) {
+        unknown = false;
         if (std == "c89") {
             return Standards::C89;
         }
@@ -85,7 +88,8 @@ struct Standards {
         if (std == "c23") {
             return Standards::C23;
         }
-        return Standards::CInvalid;
+        unknown = true;
+        return Standards::CLatest;
     }
     bool setCPP(std::string str) {
         stdValue = str;
@@ -112,12 +116,15 @@ struct Standards {
             return "c++23";
         case CPP26:
             return "c++26";
-        case CPPInvalid:
-            return "";
         }
         return "";
     }
     static cppstd_t getCPP(const std::string &std) {
+        bool _unused;
+        return getCPP(std, _unused);
+    }
+    static cppstd_t getCPP(const std::string &std, bool &unknown) {
+        unknown = false;
         if (std == "c++03") {
             return Standards::CPP03;
         }
@@ -139,7 +146,8 @@ struct Standards {
         if (std == "c++26") {
             return Standards::CPP26;
         }
-        return Standards::CPPInvalid;
+        unknown = true;
+        return Standards::CPPLatest;
     }
 };