diff --git a/test-linuxcnc-rs274-native.sh b/test-linuxcnc-rs274-native.sh
index e8a2cda..dfa3d83 100755
--- a/test-linuxcnc-rs274-native.sh
+++ b/test-linuxcnc-rs274-native.sh
@@ -746,9 +746,13 @@ CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linux
 CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_machine_coordinates.ngc >"$output_dir/cnc_sim_linuxcnc_machine_coordinates.json"
 CNC_SIM_RS274_VAR="$var_file" "$build_dir/linuxcnc_rs274_dump" tests/gcode/linuxcnc_cutter_comp.ngc >"$output_dir/cnc_sim_linuxcnc_cutter_comp.json"
 # Source basis: LinuxCNC src/emc/rs274ngc/interp_convert.cc rejects
-# M6, M66, G43, G71.0, and G98/G99 while cutter compensation is active;
-# compensated corner and G40 exit checks also reject gouging/arc exits.
+# G28/G30, G54-G59.3, G61/G64, M6, M66, G43, G71.0, and G98/G99 while
+# cutter compensation is active; compensated corner and G40 exit checks also
+# reject gouging/arc exits.
 cutter_comp_execution_error_cases=(
+    "linuxcnc_cutter_comp_control_mode_error|Cannot change control mode with cutter radius compensation on"
+    "linuxcnc_cutter_comp_coordinate_system_error|Cannot change coordinate systems with cutter radius compensation on"
+    "linuxcnc_cutter_comp_home_error|Cannot use g28 or g30 with cutter radius comp"
     "linuxcnc_cutter_comp_tool_change_error|Cannot change tools with cutter radius compensation on"
     "linuxcnc_cutter_comp_wait_input_error|Cannot wait for digital input with cutter radius compensation on"
     "linuxcnc_cutter_comp_tool_offset_error|Cannot change tool offset with cutter radius compensation on"
diff --git a/test-linuxcnc-source-link.sh b/test-linuxcnc-source-link.sh
index 1228729..6e3f975 100755
--- a/test-linuxcnc-source-link.sh
+++ b/test-linuxcnc-source-link.sh
@@ -1454,6 +1454,26 @@ fi
 grep -q "Cannot change tool offset with cutter radius compensation on" \
     "$output_dir/cnc_sim_linuxcnc_source_cutter_comp_tool_offset_error.err"
 # Source basis: LinuxCNC src/emc/rs274ngc/interp_convert.cc
+# convert_control_mode(), convert_coordinate_system(), and convert_home()
+# reject control-mode changes, coordinate-system changes, and G28/G30 while
+# cutter radius compensation is active.
+cutter_comp_g_error_cases=(
+    "linuxcnc_cutter_comp_control_mode_error|Cannot change control mode with cutter radius compensation on"
+    "linuxcnc_cutter_comp_coordinate_system_error|Cannot change coordinate systems with cutter radius compensation on"
+    "linuxcnc_cutter_comp_home_error|Cannot use g28 or g30 with cutter radius comp"
+)
+for case in "${cutter_comp_g_error_cases[@]}"; do
+    fixture=${case%%|*}
+    expected=${case#*|}
+    if CNC_SIM_RS274_FILE_MODE=1 CNC_SIM_RS274_VAR="$var_file" \
+        "$build_dir/linuxcnc_rs274_source_dump" "tests/gcode/$fixture.ngc" \
+        >"$output_dir/cnc_sim_linuxcnc_source_$fixture.json" 2>"$output_dir/cnc_sim_linuxcnc_source_$fixture.err"; then
+        echo "expected $fixture.ngc to fail" >&2
+        exit 1
+    fi
+    grep -Fq "$expected" "$output_dir/cnc_sim_linuxcnc_source_$fixture.err"
+done
+# Source basis: LinuxCNC src/emc/rs274ngc/interp_convert.cc
 # convert_m() rejects M63-M65/M67-M68/M48-M53 while cutter radius
 # compensation is active before enqueueing digital/analog output or override
 # canon side effects.
diff --git a/tests/gcode/linuxcnc_cutter_comp_control_mode_error.ngc b/tests/gcode/linuxcnc_cutter_comp_control_mode_error.ngc
new file mode 100644
index 0000000..797aa3b
--- /dev/null
+++ b/tests/gcode/linuxcnc_cutter_comp_control_mode_error.ngc
@@ -0,0 +1,3 @@
+G21 G90 G17
+G41 D1
+G64
diff --git a/tests/gcode/linuxcnc_cutter_comp_coordinate_system_error.ngc b/tests/gcode/linuxcnc_cutter_comp_coordinate_system_error.ngc
new file mode 100644
index 0000000..d2f13ee
--- /dev/null
+++ b/tests/gcode/linuxcnc_cutter_comp_coordinate_system_error.ngc
@@ -0,0 +1,3 @@
+G21 G90 G17
+G41 D1
+G55
diff --git a/tests/gcode/linuxcnc_cutter_comp_home_error.ngc b/tests/gcode/linuxcnc_cutter_comp_home_error.ngc
new file mode 100644
index 0000000..241a16a
--- /dev/null
+++ b/tests/gcode/linuxcnc_cutter_comp_home_error.ngc
@@ -0,0 +1,3 @@
+G21 G90 G17
+G41 D1
+G28