diff --git a/test-linuxcnc-rs274-native.sh b/test-linuxcnc-rs274-native.sh
index f11f7b9..c081a03 100755
--- a/test-linuxcnc-rs274-native.sh
+++ b/test-linuxcnc-rs274-native.sh
@@ -500,6 +500,7 @@ done
 # geometry before issuing straight or synchronized threading motion.
 threading_convert_error_cases=(
     "linuxcnc_g1_zero_feed_error|Cannot do g1 with zero feed rate"
+    "linuxcnc_g1_inverse_time_missing_f_error|F word missing with inverse time g1 move"
     "linuxcnc_g33_stopped_spindle_error|Spindle not turning in G33"
     "linuxcnc_g33_1_stopped_spindle_error|Spindle not turning in G33.1"
     "linuxcnc_g33_spindle_dollar_out_of_range_error|Invalid spindle (\$) number in G33 move"
diff --git a/test-linuxcnc-source-link.sh b/test-linuxcnc-source-link.sh
index e5ec5c3..9f6ad41 100755
--- a/test-linuxcnc-source-link.sh
+++ b/test-linuxcnc-source-link.sh
@@ -1084,6 +1084,7 @@ done
 # geometry before issuing straight or synchronized threading motion.
 threading_convert_error_cases=(
     "linuxcnc_g1_zero_feed_error|Cannot do g1 with zero feed rate"
+    "linuxcnc_g1_inverse_time_missing_f_error|F word missing with inverse time g1 move"
     "linuxcnc_g33_stopped_spindle_error|Spindle not turning in G33"
     "linuxcnc_g33_1_stopped_spindle_error|Spindle not turning in G33.1"
     "linuxcnc_g33_spindle_dollar_out_of_range_error|Invalid spindle (\$) number in G33 move"
diff --git a/tests/gcode/linuxcnc_g1_inverse_time_missing_f_error.ngc b/tests/gcode/linuxcnc_g1_inverse_time_missing_f_error.ngc
new file mode 100644
index 0000000..138867b
--- /dev/null
+++ b/tests/gcode/linuxcnc_g1_inverse_time_missing_f_error.ngc
@@ -0,0 +1,3 @@
+G21 G90
+G93
+G1 X1