diff --git a/cython/python_solvespace/slvs.pyx b/cython/python_solvespace/slvs.pyx
index 8eb7357d..124b74b6 100644
--- a/cython/python_solvespace/slvs.pyx
+++ b/cython/python_solvespace/slvs.pyx
@@ -17,7 +17,7 @@ from collections import Counter
 
 cpdef tuple quaternion_u(double qw, double qx, double qy, double qz):
     cdef double x, y, z
-    Slvs_QuaternionV(qw, qx, qy, qz, &x, &y, &z)
+    Slvs_QuaternionU(qw, qx, qy, qz, &x, &y, &z)
     return x, y, z