diff --git a/src/libslic3r/GCode.cpp b/src/libslic3r/GCode.cpp
index 138f6ea72..ce646d1d3 100644
--- a/src/libslic3r/GCode.cpp
+++ b/src/libslic3r/GCode.cpp
@@ -1694,11 +1694,12 @@ void GCode::print_machine_envelope(GCodeOutputStream &file, Print &print)
             int(print.config().machine_max_acceleration_y.values.front() + 0.5),
             int(print.config().machine_max_acceleration_z.values.front() + 0.5),
             int(print.config().machine_max_acceleration_e.values.front() + 0.5));
-        file.write_format("M203 X%d Y%d Z%d E%d ; sets maximum feedrates, mm/sec (or mm/min for RRF)\n",
+        file.write_format("M203 X%d Y%d Z%d E%d ; sets maximum feedrates, %s\n",
             int(print.config().machine_max_feedrate_x.values.front() * factor + 0.5),
             int(print.config().machine_max_feedrate_y.values.front() * factor + 0.5),
             int(print.config().machine_max_feedrate_z.values.front() * factor + 0.5),
-            int(print.config().machine_max_feedrate_e.values.front() * factor + 0.5));
+            int(print.config().machine_max_feedrate_e.values.front() * factor + 0.5),
+            factor == 60 ? "mm / min" : "mm / sec");
 
         // Now M204 - acceleration. This one is quite hairy thanks to how Marlin guys care about
         // backwards compatibility: https://github.com/prusa3d/PrusaSlicer/issues/1089
@@ -1707,7 +1708,7 @@ void GCode::print_machine_envelope(GCodeOutputStream &file, Print &print)
         int travel_acc = flavor == gcfMarlinLegacy
                        ? int(print.config().machine_max_acceleration_extruding.values.front() + 0.5)
                        : int(print.config().machine_max_acceleration_travel.values.front() + 0.5);
-        // Retract acceleration not accepeted in M204 in RRF
+        // Retract acceleration not accepted in M204 in RRF
         if (flavor == gcfRepRapFirmware)
             file.write_format("M204 P%d T%d ; sets acceleration (P, T), mm/sec^2\n",
                 int(print.config().machine_max_acceleration_extruding.values.front() + 0.5),
@@ -1726,11 +1727,14 @@ void GCode::print_machine_envelope(GCodeOutputStream &file, Print &print)
             print.config().machine_max_jerk_y.values.front() * factor,
             print.config().machine_max_jerk_z.values.front() * factor,
             print.config().machine_max_jerk_e.values.front() * factor);
-        // M205 Sn Tn not supported in RRF
         if (flavor != gcfRepRapFirmware)
             file.write_format("M205 S%d T%d ; sets the minimum extruding and travel feed rate, mm/sec\n",
                 int(print.config().machine_min_extruding_rate.values.front() + 0.5),
                 int(print.config().machine_min_travel_rate.values.front() + 0.5));
+        else {
+            // M205 Sn Tn not supported in RRF. They use M203 Inn to set minimum feedrate for
+            // all moves. This is currently not implemented.
+        }
     }
 }
 
diff --git a/src/slic3r/GUI/Tab.cpp b/src/slic3r/GUI/Tab.cpp
index 2fc54465a..044a0c77d 100644
--- a/src/slic3r/GUI/Tab.cpp
+++ b/src/slic3r/GUI/Tab.cpp
@@ -2926,13 +2926,13 @@ void TabPrinter::toggle_options()
     if (!m_active_page || m_presets->get_edited_preset().printer_technology() == ptSLA)
         return;
 
+    const GCodeFlavor flavor = m_config->option<ConfigOptionEnum<GCodeFlavor>>("gcode_flavor")->value;
     bool have_multiple_extruders = m_extruders_count > 1;
     if (m_active_page->title() == "Custom G-code")
         toggle_option("toolchange_gcode", have_multiple_extruders);
     if (m_active_page->title() == "General") {
         toggle_option("single_extruder_multi_material", have_multiple_extruders);
 
-        auto flavor = m_config->option<ConfigOptionEnum<GCodeFlavor>>("gcode_flavor")->value;
         bool is_marlin_flavor = flavor == gcfMarlinLegacy || flavor == gcfMarlinFirmware;
         // Disable silent mode for non-marlin firmwares.
         toggle_option("silent_mode", is_marlin_flavor);
@@ -3002,9 +3002,9 @@ void TabPrinter::toggle_options()
     }
 
     if (m_active_page->title() == "Machine limits" && m_machine_limits_description_line) {
-        assert(m_config->option<ConfigOptionEnum<GCodeFlavor>>("gcode_flavor")->value == gcfMarlinLegacy
-            || m_config->option<ConfigOptionEnum<GCodeFlavor>>("gcode_flavor")->value == gcfMarlinFirmware
-            || m_config->option<ConfigOptionEnum<GCodeFlavor>>("gcode_flavor")->value == gcfRepRapFirmware);
+        assert(flavor == gcfMarlinLegacy
+            || flavor == gcfMarlinFirmware
+            || flavor == gcfRepRapFirmware);
 		const auto *machine_limits_usage = m_config->option<ConfigOptionEnum<MachineLimitsUsage>>("machine_limits_usage");
 		bool enabled = machine_limits_usage->value != MachineLimitsUsage::Ignore;
         bool silent_mode = m_config->opt_bool("silent_mode");
@@ -3963,9 +3963,7 @@ void TabPrinter::update_machine_limits_description(const MachineLimitsUsage usag
 		break;
 	case MachineLimitsUsage::TimeEstimateOnly:
 		text = _L("Machine limits will NOT be emitted to G-code, however they will be used to estimate print time, "
-			      "which may therefore not be accurate as the printer may apply a different set of machine limits. "
-                  "This newly works with RepRapFirmware to estimate time, but the algorithm is unchanged from Marlin. "
-                  "Estimates work well when machine limits are accurately described.");
+			      "which may therefore not be accurate as the printer may apply a different set of machine limits.");
 		break;
 	case MachineLimitsUsage::Ignore:
 		text = _L("Machine limits are not set, therefore the print time estimate may not be accurate.");