diff --git a/test-linuxcnc-rs274-native.sh b/test-linuxcnc-rs274-native.sh
index 2dd9b40..3efb453 100755
--- a/test-linuxcnc-rs274-native.sh
+++ b/test-linuxcnc-rs274-native.sh
@@ -217,7 +217,12 @@ check_g_code_error_cases=(
     "linuxcnc_g10_invalid_l_error|Line with G10 does not have L0, L1, L10, L11, L2, or L20"
     "linuxcnc_g10_p_non_integer_error|P value not an integer with G10"
     "linuxcnc_g10_l2_p_out_of_range_error|P value out of range (0-9) with G10 L2"
+    "linuxcnc_g10_l2_p_missing_error|P value out of range (0-9) with G10 L2"
+    "linuxcnc_g10_l20_p_out_of_range_error|P value out of range (0-9) with G10 L20"
+    "linuxcnc_g10_l20_p_missing_error|P value out of range (0-9) with G10 L20"
     "linuxcnc_g10_l1_p_out_of_range_error|P value out of range with G10 L1"
+    "linuxcnc_g10_l10_p_out_of_range_error|P value out of range with G10 L10"
+    "linuxcnc_g10_l11_p_out_of_range_error|P value out of range with G10 L11"
     "linuxcnc_g53_arc_error|Must use g0 or g1 with g53"
     "linuxcnc_g53_incremental_error|Cannot use g53 incremental"
 )
@@ -232,6 +237,26 @@ for case in "${check_g_code_error_cases[@]}"; do
     fi
     grep -Fq "$expected" "$output_dir/cnc_sim_linuxcnc_$fixture.err"
 done
+# Source basis: LinuxCNC src/emc/rs274ngc/interp_convert.cc
+# convert_setup() rejects disallowed G10 L2/L20 words, and
+# convert_tool_table() rejects G10 L1 table updates without offsets.
+g10_convert_error_cases=(
+    "linuxcnc_g10_l1_without_offsets_error|G10 L1 without offsets has no effect"
+    "linuxcnc_g10_l2_i_word_error|I J words not allowed with G10 L2"
+    "linuxcnc_g10_l20_i_word_error|I J words not allowed with G10 L2"
+    "linuxcnc_g10_l20_r_word_error|R not allowed in G10 L20"
+)
+for case in "${g10_convert_error_cases[@]}"; do
+    fixture=${case%%|*}
+    expected=${case#*|}
+    if CNC_SIM_RS274_VAR="$var_file" \
+        "$build_dir/linuxcnc_rs274_dump" "tests/gcode/$fixture.ngc" \
+        >"$output_dir/cnc_sim_linuxcnc_$fixture.json" 2>"$output_dir/cnc_sim_linuxcnc_$fixture.err"; then
+        echo "expected $fixture.ngc to fail" >&2
+        exit 1
+    fi
+    grep -Fq "$expected" "$output_dir/cnc_sim_linuxcnc_$fixture.err"
+done
 # Source basis: LinuxCNC src/emc/rs274ngc/interp_read.cc
 # read_g()/read_m() validate numeric range, known code tables from
 # interp_array.cc, and same-modal-group conflicts while filling a block.
diff --git a/test-linuxcnc-source-link.sh b/test-linuxcnc-source-link.sh
index aff4e8a..6c84c60 100755
--- a/test-linuxcnc-source-link.sh
+++ b/test-linuxcnc-source-link.sh
@@ -661,7 +661,12 @@ check_g_code_error_cases=(
     "linuxcnc_g10_invalid_l_error|Line with G10 does not have L0, L1, L10, L11, L2, or L20"
     "linuxcnc_g10_p_non_integer_error|P value not an integer with G10"
     "linuxcnc_g10_l2_p_out_of_range_error|P value out of range (0-9) with G10 L2"
+    "linuxcnc_g10_l2_p_missing_error|P value out of range (0-9) with G10 L2"
+    "linuxcnc_g10_l20_p_out_of_range_error|P value out of range (0-9) with G10 L20"
+    "linuxcnc_g10_l20_p_missing_error|P value out of range (0-9) with G10 L20"
     "linuxcnc_g10_l1_p_out_of_range_error|P value out of range with G10 L1"
+    "linuxcnc_g10_l10_p_out_of_range_error|P value out of range with G10 L10"
+    "linuxcnc_g10_l11_p_out_of_range_error|P value out of range with G10 L11"
     "linuxcnc_g53_arc_error|Must use g0 or g1 with g53"
     "linuxcnc_g53_incremental_error|Cannot use g53 incremental"
 )
@@ -676,6 +681,26 @@ for case in "${check_g_code_error_cases[@]}"; do
     fi
     grep -Fq "$expected" "$output_dir/cnc_sim_linuxcnc_source_$fixture.err"
 done
+# Source basis: LinuxCNC src/emc/rs274ngc/interp_convert.cc
+# convert_setup() rejects disallowed G10 L2/L20 words, and
+# convert_tool_table() rejects G10 L1 table updates without offsets.
+g10_convert_error_cases=(
+    "linuxcnc_g10_l1_without_offsets_error|G10 L1 without offsets has no effect"
+    "linuxcnc_g10_l2_i_word_error|I J words not allowed with G10 L2"
+    "linuxcnc_g10_l20_i_word_error|I J words not allowed with G10 L2"
+    "linuxcnc_g10_l20_r_word_error|R not allowed in G10 L20"
+)
+for case in "${g10_convert_error_cases[@]}"; do
+    fixture=${case%%|*}
+    expected=${case#*|}
+    if CNC_SIM_RS274_VAR="$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
 CNC_SIM_RS274_VAR="$var_file" \
     "$build_dir/linuxcnc_rs274_source_dump" tests/gcode/linuxcnc_predefined_positions.ngc \
     >"$output_dir/cnc_sim_linuxcnc_source_predefined_positions.json"
diff --git a/tests/gcode/linuxcnc_g10_l10_p_out_of_range_error.ngc b/tests/gcode/linuxcnc_g10_l10_p_out_of_range_error.ngc
new file mode 100644
index 0000000..66dbeae
--- /dev/null
+++ b/tests/gcode/linuxcnc_g10_l10_p_out_of_range_error.ngc
@@ -0,0 +1,2 @@
+G21 G90
+G10 L10 P0 X0
diff --git a/tests/gcode/linuxcnc_g10_l11_p_out_of_range_error.ngc b/tests/gcode/linuxcnc_g10_l11_p_out_of_range_error.ngc
new file mode 100644
index 0000000..edc9ac2
--- /dev/null
+++ b/tests/gcode/linuxcnc_g10_l11_p_out_of_range_error.ngc
@@ -0,0 +1,2 @@
+G21 G90
+G10 L11 P0 X0
diff --git a/tests/gcode/linuxcnc_g10_l1_without_offsets_error.ngc b/tests/gcode/linuxcnc_g10_l1_without_offsets_error.ngc
new file mode 100644
index 0000000..dcca7f0
--- /dev/null
+++ b/tests/gcode/linuxcnc_g10_l1_without_offsets_error.ngc
@@ -0,0 +1,2 @@
+G21 G90
+G10 L1 P1
diff --git a/tests/gcode/linuxcnc_g10_l20_i_word_error.ngc b/tests/gcode/linuxcnc_g10_l20_i_word_error.ngc
new file mode 100644
index 0000000..f6d0518
--- /dev/null
+++ b/tests/gcode/linuxcnc_g10_l20_i_word_error.ngc
@@ -0,0 +1,2 @@
+G21 G90
+G10 L20 P1 I2
diff --git a/tests/gcode/linuxcnc_g10_l20_p_missing_error.ngc b/tests/gcode/linuxcnc_g10_l20_p_missing_error.ngc
new file mode 100644
index 0000000..28eee93
--- /dev/null
+++ b/tests/gcode/linuxcnc_g10_l20_p_missing_error.ngc
@@ -0,0 +1,2 @@
+G21 G90
+G10 L20 X1
diff --git a/tests/gcode/linuxcnc_g10_l20_p_out_of_range_error.ngc b/tests/gcode/linuxcnc_g10_l20_p_out_of_range_error.ngc
new file mode 100644
index 0000000..0feb6d8
--- /dev/null
+++ b/tests/gcode/linuxcnc_g10_l20_p_out_of_range_error.ngc
@@ -0,0 +1,2 @@
+G21 G90
+G10 L20 P10 X1
diff --git a/tests/gcode/linuxcnc_g10_l20_r_word_error.ngc b/tests/gcode/linuxcnc_g10_l20_r_word_error.ngc
new file mode 100644
index 0000000..231de82
--- /dev/null
+++ b/tests/gcode/linuxcnc_g10_l20_r_word_error.ngc
@@ -0,0 +1,2 @@
+G21 G90
+G10 L20 P1 X1 R30
diff --git a/tests/gcode/linuxcnc_g10_l2_i_word_error.ngc b/tests/gcode/linuxcnc_g10_l2_i_word_error.ngc
new file mode 100644
index 0000000..d09f207
--- /dev/null
+++ b/tests/gcode/linuxcnc_g10_l2_i_word_error.ngc
@@ -0,0 +1,2 @@
+G21 G90
+G10 L2 P1 X1 I2
diff --git a/tests/gcode/linuxcnc_g10_l2_p_missing_error.ngc b/tests/gcode/linuxcnc_g10_l2_p_missing_error.ngc
new file mode 100644
index 0000000..894e1b2
--- /dev/null
+++ b/tests/gcode/linuxcnc_g10_l2_p_missing_error.ngc
@@ -0,0 +1,2 @@
+G21 G90
+G10 L2 X1