diff --git a/Htmldocs/release_notes.html b/Htmldocs/release_notes.html
index fffc5dd5..31fdc636 100644
--- a/Htmldocs/release_notes.html
+++ b/Htmldocs/release_notes.html
@@ -18,6 +18,7 @@
       <li>[new] Add support for new settings codes in recently manufactured 700X110 DreamStations.</li>
       <li>[new] Add 95% flow limitation to Therapy Efficacy section on Statistics page.</li>
       <li>[fix] Correct SleepStyle machines sometimes identified as Icon machines.</li>
+      <li>[fix] --datadir option now allows fully qualified paths on Mac and Linux.</li>
       <li>[fix] Update copyright notices in html files.</li>
       <li>[fix] Correct value display on exact data points, and near session boundaries with drift.</li>
       <li>[fix] Link to translations in Credits and Release Notes html is now translated to selected language.</li>
diff --git a/oscar/main.cpp b/oscar/main.cpp
index 9ee84374..93d68eda 100644
--- a/oscar/main.cpp
+++ b/oscar/main.cpp
@@ -366,12 +366,19 @@ int main(int argc, char *argv[]) {
                 exit(1);
             }
         } else if (args[i] == "--datadir") { // mltam's idea
-            QString datadir ;
+            QString datadir, datadirwas ;
             if ((i+1) < args.size()) {
-                datadir = args[++i];
-                if (datadir.length() < 2 || datadir.at(1) != QLatin1Char(':'))  // Allow a Windows drive letter (but not UNC)
+                datadirwas = datadir = args[++i];
+                bool havefullpath = false;
+                if (datadir.length() >= 2) {
+                    havefullpath =    (datadir.at(1) == QLatin1Char(':')) // Allow a Windows drive letter
+                                   || (datadir.at(0) == '/')              // or Linux full path
+                                   || (datadir.at(0) == '\\');
+                }
+                if (!havefullpath)
                     datadir = homeDocs+datadir;
                 settings.setValue("Settings/AppData", datadir);
+                qDebug() << "--datadir" << datadirwas << "homeDocs:" << homeDocs << "appdata:" << datadir;
 //            force_data_dir = true;
             } else {
                 fprintf(stderr, "Missing argument to --datadir\n");