diff --git a/Marlin/G26_Mesh_Validation_Tool.cpp b/Marlin/G26_Mesh_Validation_Tool.cpp
index 09dc6e324..9bddfc1f6 100644
--- a/Marlin/G26_Mesh_Validation_Tool.cpp
+++ b/Marlin/G26_Mesh_Validation_Tool.cpp
@@ -274,7 +274,7 @@
                                     // action to give the user a more responsive 'Stop'.
           set_destination_from_current();
           idle();
-          MYSERIAL0.flush(); // Prevent host M105 buffer overrun.
+          SERIAL_FLUSH(); // Prevent host M105 buffer overrun.
         }
 
         wait_for_release();
@@ -501,7 +501,7 @@
               SERIAL_EOL();
             }
             idle();
-            MYSERIAL0.flush(); // Prevent host M105 buffer overrun.
+            SERIAL_FLUSH(); // Prevent host M105 buffer overrun.
           }
       #if ENABLED(ULTRA_LCD)
         }
@@ -525,7 +525,7 @@
       }
       idle();
 
-      MYSERIAL0.flush(); // Prevent host M105 buffer overrun.
+      SERIAL_FLUSH(); // Prevent host M105 buffer overrun.
     }
     #if ENABLED(ULTRA_LCD)
       lcd_reset_status();
@@ -811,12 +811,12 @@
           #endif
 
           print_line_from_here_to_there(rx, ry, g26_layer_height, xe, ye, g26_layer_height);
-          MYSERIAL0.flush();  // Prevent host M105 buffer overrun.
+          SERIAL_FLUSH();  // Prevent host M105 buffer overrun.
         }
         if (look_for_lines_to_connect())
           goto LEAVE;
       }
-      MYSERIAL0.flush(); // Prevent host M105 buffer overrun.
+      SERIAL_FLUSH(); // Prevent host M105 buffer overrun.
     } while (--g26_repeats && location.x_index >= 0 && location.y_index >= 0);
 
     LEAVE:
diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index 8b40524c9..34a82140a 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -11981,7 +11981,7 @@ void process_next_command() {
  */
 void FlushSerialRequestResend() {
   //char command_queue[cmd_queue_index_r][100]="Resend:";
-  MYSERIAL0.flush();
+  SERIAL_FLUSH();
   SERIAL_PROTOCOLPGM(MSG_RESEND);
   SERIAL_PROTOCOLLN(gcode_LastN + 1);
   ok_to_send();
diff --git a/Marlin/serial.h b/Marlin/serial.h
index 5e9d9fbce..acad50266 100644
--- a/Marlin/serial.h
+++ b/Marlin/serial.h
@@ -48,6 +48,11 @@ extern const char errormagic[] PROGMEM;
 #define SERIAL_PRINTLN(x,b)    MYSERIAL0.println(x,b)
 #define SERIAL_PRINTF(args...) MYSERIAL0.printf(args)
 
+#define SERIAL_FLUSH()         MYSERIAL0.flush()
+#if TX_BUFFER_SIZE > 0
+  #define SERIAL_FLUSHTX()     MYSERIAL0.flushTX()
+#endif
+
 #define SERIAL_PROTOCOLCHAR(x)              SERIAL_CHAR(x)
 #define SERIAL_PROTOCOL(x)                  MYSERIAL0.print(x)
 #define SERIAL_PROTOCOL_F(x,y)              MYSERIAL0.print(x,y)
diff --git a/Marlin/ubl.cpp b/Marlin/ubl.cpp
index f6a9a6873..92eacacdf 100644
--- a/Marlin/ubl.cpp
+++ b/Marlin/ubl.cpp
@@ -199,7 +199,7 @@
         if (map_type == 1 && i < GRID_MAX_POINTS_X - 1) SERIAL_CHAR(',');
 
         #if TX_BUFFER_SIZE > 0
-          MYSERIAL0.flushTX();
+          SERIAL_FLUSHTX();
         #endif
         safe_delay(15);
         if (map_type == 0) {
diff --git a/Marlin/ubl_G29.cpp b/Marlin/ubl_G29.cpp
index 8b8ebc365..bd232cb27 100644
--- a/Marlin/ubl_G29.cpp
+++ b/Marlin/ubl_G29.cpp
@@ -763,7 +763,7 @@
           const float measured_z = probe_pt(rawx, rawy, stow_probe, g29_verbose_level); // TODO: Needs error handling
           z_values[location.x_index][location.y_index] = measured_z;
         }
-        MYSERIAL0.flush(); // Prevent host M105 buffer overrun.
+        SERIAL_FLUSH(); // Prevent host M105 buffer overrun.
 
       } while (location.x_index >= 0 && --max_iterations);
 
@@ -902,7 +902,7 @@
           SERIAL_PROTOCOL_F(z_values[location.x_index][location.y_index], 6);
           SERIAL_EOL();
         }
-        MYSERIAL0.flush(); // Prevent host M105 buffer overrun.
+        SERIAL_FLUSH(); // Prevent host M105 buffer overrun.
       } while (location.x_index >= 0 && location.y_index >= 0);
 
       if (do_ubl_mesh_map) display_map(g29_map_type);  // show user where we're probing
@@ -1414,7 +1414,7 @@
             do_blocking_move_to_z(h_offset + new_z); // Move the nozzle as the point is edited
           #endif
           idle();
-          MYSERIAL0.flush(); // Prevent host M105 buffer overrun.
+          SERIAL_FLUSH(); // Prevent host M105 buffer overrun.
         } while (!is_lcd_clicked());
 
         if (!lcd_map_control) lcd_return_to_status();