diff --git a/tools/qfcc/test/Makemodule.am b/tools/qfcc/test/Makemodule.am
index fdd500dbe..eca0d5376 100644
--- a/tools/qfcc/test/Makemodule.am
+++ b/tools/qfcc/test/Makemodule.am
@@ -51,6 +51,7 @@ test_progs_dat=\
 	tools/qfcc/test/ptrfunc.dat \
 	tools/qfcc/test/ptrstructcast.dat \
 	tools/qfcc/test/motor-point.dat \
+	tools/qfcc/test/motor-xform.dat \
 	tools/qfcc/test/quaternion.dat \
 	tools/qfcc/test/return-ivar.dat \
 	tools/qfcc/test/return-postop.dat \
@@ -621,6 +622,16 @@ tools/qfcc/test/motor-point.run: $(qfcc_test_run_deps)
 include $(motor_point_dep) # am--include-marker
 r_depfiles_remade += $(motor_point_dep)
 
+tools_qfcc_test_motor_xform_dat_SOURCES=tools/qfcc/test/motor-xform.r
+motor_xform_obj=$(tools_qfcc_test_motor_xform_dat_SOURCES:.r=.o)
+motor_xform_dep=$(call qcautodep,$(tools_qfcc_test_motor_xform_dat_SOURCES))
+tools/qfcc/test/motor-xform.dat$(EXEEXT): $(motor_xform_obj) $(QFCC_DEP)
+	$(V_QFCCLD)$(QLINK) -o $@ $(motor_xform_obj)
+tools/qfcc/test/motor-xform.run: $(qfcc_test_run_deps)
+	@$(top_srcdir)/tools/qfcc/test/build-run $@
+include $(motor_xform_dep) # am--include-marker
+r_depfiles_remade += $(motor_xform_dep)
+
 tools_qfcc_test_quaternion_dat_SOURCES=tools/qfcc/test/quaternion.r
 quaternion_obj=$(tools_qfcc_test_quaternion_dat_SOURCES:.r=.o)
 quaternion_dep=$(call qcautodep,$(tools_qfcc_test_quaternion_dat_SOURCES))
diff --git a/tools/qfcc/test/motor-xform.r b/tools/qfcc/test/motor-xform.r
new file mode 100644
index 000000000..9254f1ef5
--- /dev/null
+++ b/tools/qfcc/test/motor-xform.r
@@ -0,0 +1,86 @@
+#include "test-harness.h"
+
+typedef @algebra(float(3,0,1)) PGA;
+typedef PGA.group_mask(0xa) bivector_t;
+typedef PGA.group_mask(0x1e) motor_t;
+typedef PGA.tvec point_t;
+typedef PGA.vec  plane_t;
+
+typedef struct {
+	vec4        trans;
+	vec4        rot;
+} xform_t;
+
+motor_t
+make_motor (vec4 translation, vec4 rotation)
+{
+	@algebra(PGA) {
+		auto dt = (PGA.group_mask (0x18)) translation;
+		auto q = (PGA.group_mask(0x06)) rotation;
+		motor_t t = { .scalar = 1, .bvecp = -dt.bvecp / 2 };
+		motor_t r = { .scalar = q.scalar, .bvect = q.bvect };
+		motor_t m = t * r;
+		return m;
+	}
+}
+
+xform_t
+set_transform (motor_t m, int p)
+{
+	@algebra (PGA) {
+		auto r = ⋆(m * e0123);
+		auto t = (m * ⋆(m * e0123)).bvecp;
+		vec4 rot = (vec4) r;
+		vec4 trans = [(vec3)t * -2, 1];
+		if (p) printf ("set_transform: %q %q\n", rot, trans);
+		return {trans, rot};
+	}
+}
+
+PGA.scalar rh = 0.7071067811865476;
+
+int
+main()
+{
+	motor_t start = make_motor ({ 10, 4, -1.5, 0 }, { 0, 0, 0, 1 });
+	vec3 bvt = { 0, 0, rh };
+	vec3 bvp = { 0, -6*rh, 0 };
+	motor_t delta = {
+		.scalar = rh,
+		.bvect = (PGA.bvect) bvt,
+		.bvecp = (PGA.bvecp) bvp,
+	};
+	motor_t testm = delta * start;
+	printf ("start: %g %v %v %g\n",
+			start.scalar, start.bvect, start.bvecp, start.qvec);
+	printf ("delta: %g %v %v %g\n",
+			delta.scalar, delta.bvect, delta.bvecp, delta.qvec);
+	printf ("testm: %g %v %v %g\n",
+			testm.scalar, testm.bvect, testm.bvecp, testm.qvec);
+	auto xform = set_transform (testm, 1);
+	printf ("xform: %.9q %.9q\n", xform.trans, xform.rot);
+	if (start.scalar != 1 || (vec3) start.bvect != '0 0 0'
+		|| (vec3) start.bvecp != '-5 -2 0.75'
+		|| (PGA.scalar) start.qvec != 0) {
+		printf ("start incorrect\n");
+		return 1;
+	}
+	if (delta.scalar != rh || (vec3) delta.bvect != '0 0 0.7071067811865476'
+		|| (vec3) delta.bvecp != '0 -4.242640687119285 0'
+		|| (PGA.scalar) delta.qvec != 0) {
+		printf ("delta incorrect\n");
+		return 1;
+	}
+	if (testm.scalar != rh || (vec3) testm.bvect != '0 0 0.7071067811865476'
+		|| (vec3) testm.bvecp != '-4.949747468305833 -2.1213203435596424 0.5303300858899106'
+		|| (PGA.scalar) testm.qvec != 0.5303300858899106) {
+		printf ("testm incorrect\n");
+		return 1;
+	}
+	if (xform.trans != '10 -4 -1.49999988 1'
+		|| xform.rot != '0 0 -0.7071067811865476 0.7071067811865476') {
+		printf ("xform incorrect\n");
+		return 1;
+	}
+	return 0;
+}