diff --git a/lib/path.cpp b/lib/path.cpp
index 6770267cfda..91ccfabc213 100644
--- a/lib/path.cpp
+++ b/lib/path.cpp
@@ -449,9 +449,13 @@ bool Path::exists(const std::string &path, bool* isdir)
     return type == S_IFREG;
 }
 
-std::string Path::join(const std::string& path1, const std::string& path2) {
+std::string Path::join(std::string path1, std::string path2)
+{
+    path1 = fromNativeSeparators(std::move(path1));
+    path2 = fromNativeSeparators(std::move(path2));
     if (path1.empty() || path2.empty())
         return path1 + path2;
+    // this matches the behavior of std::filesystem::path::operator/=() and os.path.join()
     if (path2.front() == '/')
         return path2;
     return ((path1.back() == '/') ? path1 : (path1 + "/")) + path2;
diff --git a/lib/path.h b/lib/path.h
index 9f13da09236..23db06c4e50 100644
--- a/lib/path.h
+++ b/lib/path.h
@@ -201,9 +201,11 @@ class CPPCHECKLIB Path {
     static bool exists(const std::string &path, bool* isdir = nullptr);
 
     /**
-     * join 2 paths with '/' separators
+     * @brief join 2 paths with '/' separators
+     * if path2 is an absolute path path1 will be dismissed.
+     * @return the joined path with normalized slashes
      */
-    static std::string join(const std::string& path1, const std::string& path2);
+    static std::string join(std::string path1, std::string path2);
 };
 
 /// @}
diff --git a/test/testpath.cpp b/test/testpath.cpp
index 44d5f10a30b..7c181e28afb 100644
--- a/test/testpath.cpp
+++ b/test/testpath.cpp
@@ -172,11 +172,36 @@ class TestPath : public TestFixture {
     }
 
     void join() const {
+        ASSERT_EQUALS("", Path::join("", ""));
+        ASSERT_EQUALS("b", Path::join("", "b"));
+        ASSERT_EQUALS("/b", Path::join("", "/b"));
+        ASSERT_EQUALS("/b", Path::join("", "\\b"));
+
         ASSERT_EQUALS("a", Path::join("a", ""));
-        ASSERT_EQUALS("a", Path::join("", "a"));
         ASSERT_EQUALS("a/b", Path::join("a", "b"));
-        ASSERT_EQUALS("a/b", Path::join("a/", "b"));
         ASSERT_EQUALS("/b", Path::join("a", "/b"));
+        ASSERT_EQUALS("/b", Path::join("a", "\\b"));
+
+        ASSERT_EQUALS("a/", Path::join("a/", ""));
+        ASSERT_EQUALS("a/b", Path::join("a/", "b"));
+        ASSERT_EQUALS("/b", Path::join("a/", "/b"));
+        ASSERT_EQUALS("/b", Path::join("a/", "\\b"));
+
+        ASSERT_EQUALS("a/", Path::join("a\\", ""));
+        ASSERT_EQUALS("a/b", Path::join("a\\", "b"));
+        ASSERT_EQUALS("/b", Path::join("a\\", "/b"));
+        ASSERT_EQUALS("/b", Path::join("a\\", "\\b"));
+
+        // TODO: how to absolute Windows path in path2?
+        //ASSERT_EQUALS("", Path::join("a", "s:/b"));
+
+        //ASSERT_EQUALS("", Path::join("S:\\a", "S:/b"));
+        //ASSERT_EQUALS("", Path::join("S:\\a", "S:\\b"));
+        //ASSERT_EQUALS("", Path::join("S:\\a", "/b"));
+
+        //ASSERT_EQUALS("", Path::join("S:/a", "S:/b"));
+        //ASSERT_EQUALS("", Path::join("S:/a", "S:\\b"));
+        //ASSERT_EQUALS("", Path::join("S:/a", "/b"));
     }
 
     void isDirectory() const {