diff --git a/Marlin/I2CPositionEncoder.cpp b/Marlin/I2CPositionEncoder.cpp
index 84334812f..6422b4f2f 100644
--- a/Marlin/I2CPositionEncoder.cpp
+++ b/Marlin/I2CPositionEncoder.cpp
@@ -117,7 +117,7 @@
 
             SERIAL_ECHOPGM("New position reads as ");
             SERIAL_ECHO(get_position());
-            SERIAL_ECHOPGM("(");
+            SERIAL_CHAR('(');
             SERIAL_ECHO(mm_from_count(get_position()));
             SERIAL_ECHOLNPGM(")");
           #endif
diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index 808da5842..135832c01 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -10029,7 +10029,7 @@ inline void gcode_M502() {
 
     if (!ijk) {
       SERIAL_ECHO_START();
-      SERIAL_ECHO(MSG_SKEW_FACTOR " XY: ");
+      SERIAL_ECHOPGM(MSG_SKEW_FACTOR " XY: ");
       SERIAL_ECHO_F(planner.xy_skew_factor, 6);
       SERIAL_EOL();
       #if ENABLED(SKEW_CORRECTION_FOR_Z)
@@ -12880,7 +12880,8 @@ void prepare_move_to_destination() {
     if (angular_travel == 0 && current_position[p_axis] == cart[p_axis] && current_position[q_axis] == cart[q_axis])
       angular_travel = RADIANS(360);
 
-    const float mm_of_travel = HYPOT(angular_travel * radius, FABS(linear_travel));
+    const float flat_mm = radius * angular_travel,
+                mm_of_travel = linear_travel ? HYPOT(flat_mm, linear_travel) : flat_mm;
     if (mm_of_travel < 0.001) return;
 
     uint16_t segments = FLOOR(mm_of_travel / (MM_PER_ARC_SEGMENT));
diff --git a/Marlin/configuration_store.cpp b/Marlin/configuration_store.cpp
index 9fc000a53..2d3d5fbd9 100644
--- a/Marlin/configuration_store.cpp
+++ b/Marlin/configuration_store.cpp
@@ -2228,7 +2228,7 @@ void MarlinSettings::reset() {
       }
       CONFIG_ECHO_START;
       #if ENABLED(SKEW_CORRECTION_FOR_Z)
-        SERIAL_ECHO("  M852 I");
+        SERIAL_ECHOPGM("  M852 I");
         SERIAL_ECHO_F(LINEAR_UNIT(planner.xy_skew_factor), 6);
         SERIAL_ECHOPGM(" J");
         SERIAL_ECHO_F(LINEAR_UNIT(planner.xz_skew_factor), 6);
@@ -2236,7 +2236,7 @@ void MarlinSettings::reset() {
         SERIAL_ECHO_F(LINEAR_UNIT(planner.yz_skew_factor), 6);
         SERIAL_EOL();
       #else
-        SERIAL_ECHO("  M852 S");
+        SERIAL_ECHOPGM("  M852 S");
         SERIAL_ECHO_F(LINEAR_UNIT(planner.xy_skew_factor), 6);
         SERIAL_EOL();
       #endif
@@ -2251,7 +2251,7 @@ void MarlinSettings::reset() {
         SERIAL_ECHOLNPGM("Stepper driver current:");
       }
       CONFIG_ECHO_START;
-      SERIAL_ECHO("  M906");
+      SERIAL_ECHOPGM("  M906");
       #if ENABLED(X_IS_TMC2130) || ENABLED(X_IS_TMC2208)
         SERIAL_ECHOPAIR(" X ", stepperX.getCurrent());
       #endif
@@ -2297,7 +2297,7 @@ void MarlinSettings::reset() {
         SERIAL_ECHOLNPGM("Sensorless homing threshold:");
       }
       CONFIG_ECHO_START;
-      SERIAL_ECHO("  M914");
+      SERIAL_ECHOPGM("  M914");
       #if ENABLED(X_IS_TMC2130)
         SERIAL_ECHOPAIR(" X", stepperX.sgt());
       #endif
diff --git a/Marlin/gcode.cpp b/Marlin/gcode.cpp
index fd26aaea1..0fdd2bc9c 100644
--- a/Marlin/gcode.cpp
+++ b/Marlin/gcode.cpp
@@ -282,7 +282,7 @@ void GCodeParser::unknown_command_error() {
     #else
       SERIAL_ECHOPAIR(" args: \"", command_args);
     #endif
-    SERIAL_ECHOPGM("\"");
+    SERIAL_CHAR('"');
     if (string_arg) {
       SERIAL_ECHOPGM(" string: \"");
       SERIAL_ECHO(string_arg);
diff --git a/Marlin/planner.cpp b/Marlin/planner.cpp
index adbf14250..7486e3bd5 100644
--- a/Marlin/planner.cpp
+++ b/Marlin/planner.cpp
@@ -362,7 +362,7 @@ void Planner::recalculate_trapezoids() {
   }
 }
 
-/*
+/**
  * Recalculate the motion plan according to the following algorithm:
  *
  *   1. Go over every block in reverse order...
@@ -392,7 +392,6 @@ void Planner::recalculate() {
   recalculate_trapezoids();
 }
 
-
 #if ENABLED(AUTOTEMP)
 
   void Planner::getHighESpeed() {
diff --git a/Marlin/printcounter.cpp b/Marlin/printcounter.cpp
index 6edc0ac8c..794a1995e 100644
--- a/Marlin/printcounter.cpp
+++ b/Marlin/printcounter.cpp
@@ -140,7 +140,7 @@ void PrintCounter::showStats() {
 
   SERIAL_ECHOPGM("Filament used: ");
   SERIAL_ECHO(this->data.filamentUsed / 1000);
-  SERIAL_ECHOPGM("m");
+  SERIAL_CHAR('m');
 
   SERIAL_EOL();
 }