diff --git a/src/source.cpp b/src/source.cpp
index 9b7c5cc..47b5ba3 100644
--- a/src/source.cpp
+++ b/src/source.cpp
@@ -106,15 +106,10 @@ Glib::RefPtr<Gsv::Language> Source::guess_language(const boost::filesystem::path
   else if(language->get_id() == "octave" && extension == ".m") {
     // .m is used for both Octave and Objective-C, so try to differentiate
     std::ifstream input(file_path.string(), std::ios::binary);
-    std::string buffer(256, '\0');
-    input.read(&buffer[0], static_cast<std::streamsize>(buffer.size()));
-    buffer.resize(static_cast<std::size_t>(input.gcount()));
-    if(input && (buffer.find("#import ") != std::string::npos ||
-                 buffer.find("@interface ") != std::string::npos ||
-                 buffer.find("/*") != std::string::npos ||
-                 buffer.find("//") != std::string::npos)) {
+    std::string line;
+    if(input && std::getline(input, line) &&
+       (starts_with(line, "#import ") || starts_with(line, "@interface ") || starts_with(line, "/*") || starts_with(line, "//")))
       language = language_manager->get_language("objc");
-    }
   }
   return language;
 }