diff --git a/ext_src/_project.pyx b/ext_src/_project.pyx
index 8b74910..8927aed 100644
--- a/ext_src/_project.pyx
+++ b/ext_src/_project.pyx
@@ -27,7 +27,7 @@ cdef extern from "openmp.hpp" namespace "sphereproj":
 @cython.wraparound(False)
 cdef void interp3d_INTERNAL_periodic(DTYPE_t x, DTYPE_t y,
                                         DTYPE_t z,
-                                        DTYPE_t[:,:,:] d, DTYPE_t Lbox, DTYPE_t *retval) nogil:
+                                        DTYPE_t[:,:,:] d, DTYPE_t Lbox, DTYPE_t *retval) noexcept nogil:
 
     cdef int Ngrid = d.shape[0]
     cdef DTYPE_t inv_delta = Ngrid/Lbox
@@ -86,7 +86,7 @@ cdef void interp3d_INTERNAL_periodic(DTYPE_t x, DTYPE_t y,
 @cython.wraparound(False)
 cdef void ngp3d_INTERNAL_periodic(DTYPE_t x, DTYPE_t y,
                                  DTYPE_t z,
-                                 DTYPE_t[:,:,:] d, DTYPE_t Lbox, DTYPE_t *retval) nogil:
+                                 DTYPE_t[:,:,:] d, DTYPE_t Lbox, DTYPE_t *retval) noexcept nogil:
 
     cdef int Ngrid = d.shape[0]
     cdef DTYPE_t inv_delta = Ngrid/Lbox
@@ -116,7 +116,7 @@ cdef void ngp3d_INTERNAL_periodic(DTYPE_t x, DTYPE_t y,
 @cython.wraparound(False)
 cdef void ngp3d_INTERNAL(DTYPE_t x, DTYPE_t y,
                          DTYPE_t z,
-                         DTYPE_t[:,:,:] d, DTYPE_t Lbox, DTYPE_t *retval, DTYPE_t inval) nogil:
+                         DTYPE_t[:,:,:] d, DTYPE_t Lbox, DTYPE_t *retval, DTYPE_t inval) noexcept nogil:
 
     cdef int Ngrid = d.shape[0]
     cdef DTYPE_t inv_delta = Ngrid/Lbox
@@ -145,7 +145,7 @@ cdef void ngp3d_INTERNAL(DTYPE_t x, DTYPE_t y,
 @cython.wraparound(False)
 cdef void interp3d_INTERNAL(DTYPE_t x, DTYPE_t y,
                                DTYPE_t z,
-                               DTYPE_t[:,:,:] d, DTYPE_t Lbox, DTYPE_t *retval, DTYPE_t inval) nogil:
+                               DTYPE_t[:,:,:] d, DTYPE_t Lbox, DTYPE_t *retval, DTYPE_t inval) noexcept nogil:
 
     cdef int Ngrid = d.shape[0]
     cdef DTYPE_t inv_delta = Ngrid/Lbox
@@ -386,7 +386,7 @@ def interp2d(x not None, y not None,
 @cython.boundscheck(False)
 @cython.cdivision(True)
 cdef void INTERNAL_project_cic_no_mass(DTYPE_t[:,:,:] g,
-                                       DTYPE_t[:,:] x, int Ngrid, double Lbox, double shifter) nogil:
+                                       DTYPE_t[:,:] x, int Ngrid, double Lbox, double shifter) noexcept nogil:
     cdef double delta_Box = Ngrid/Lbox
     cdef int i
     cdef double a[3]
@@ -419,7 +419,7 @@ cdef void INTERNAL_project_cic_no_mass(DTYPE_t[:,:,:] g,
 @cython.boundscheck(False)
 @cython.cdivision(True)
 cdef void INTERNAL_project_cic_no_mass_periodic(DTYPE_t[:,:,:] g,
-                                                DTYPE_t[:,:] x, int Ngrid, double Lbox, double shifter) nogil:
+                                                DTYPE_t[:,:] x, int Ngrid, double Lbox, double shifter) noexcept nogil:
     cdef double delta_Box = Ngrid/Lbox
     cdef int i
     cdef double a[3]
@@ -462,7 +462,7 @@ cdef void INTERNAL_project_cic_no_mass_periodic(DTYPE_t[:,:,:] g,
 cdef void INTERNAL_project_cic_with_mass(DTYPE_t[:,:,:] g,
                                          DTYPE_t[:,:] x,
                                          DTYPE_t[:] mass,
-                                         int Ngrid, double Lbox, double shifter) nogil:
+                                         int Ngrid, double Lbox, double shifter) noexcept nogil:
     cdef double delta_Box = Ngrid/Lbox
     cdef int i
     cdef double a[3]
@@ -499,7 +499,7 @@ cdef void INTERNAL_project_cic_with_mass(DTYPE_t[:,:,:] g,
 cdef void INTERNAL_project_cic_with_mass_periodic(DTYPE_t[:,:,:] g,
                                                   DTYPE_t[:,:] x,
                                                   DTYPE_t[:] mass,
-                                                  int Ngrid, double Lbox, double shifter) nogil:
+                                                  int Ngrid, double Lbox, double shifter) noexcept nogil:
     cdef double half_Box = 0.5*Lbox, m0
     cdef double delta_Box = Ngrid/Lbox
     cdef int i
@@ -680,7 +680,7 @@ cdef DTYPE_t cube_integral_trilin(DTYPE_t u[3], DTYPE_t u0[3], int r[1], DTYPE_t
 
 @cython.boundscheck(False)
 cdef DTYPE_t integrator0(DTYPE_t[:,:,:] density,
-                         DTYPE_t u[3], DTYPE_t u0[3], int u_delta[3], int iu0[3], int jumper[1], DTYPE_t alpha_max) nogil:
+                         DTYPE_t u[3], DTYPE_t u0[3], int u_delta[3], int iu0[3], int jumper[1], DTYPE_t alpha_max) noexcept nogil:
     cdef DTYPE_t d
 
     d = density[iu0[0], iu0[1], iu0[2]]
@@ -689,7 +689,7 @@ cdef DTYPE_t integrator0(DTYPE_t[:,:,:] density,
 
 @cython.boundscheck(False)
 cdef DTYPE_t integrator1(DTYPE_t[:,:,:] density,
-                         DTYPE_t u[3], DTYPE_t u0[3], int u_delta[3], int iu0[3], int jumper[1], DTYPE_t alpha_max) nogil:
+                         DTYPE_t u[3], DTYPE_t u0[3], int u_delta[3], int iu0[3], int jumper[1], DTYPE_t alpha_max) noexcept nogil:
     cdef DTYPE_t vertex_value[8]
     cdef DTYPE_t d
     cdef int a[3][2]
@@ -717,7 +717,7 @@ cdef DTYPE_t integrator1(DTYPE_t[:,:,:] density,
 cdef DTYPE_t C_line_of_sight_projection(DTYPE_t[:,:,:] density,
                              DTYPE_t a_u[3],
                              DTYPE_t min_distance,
-                             DTYPE_t max_distance, DTYPE_t[:] shifter, int integrator_id) nogil except? 0:
+                             DTYPE_t max_distance, DTYPE_t[:] shifter, int integrator_id) except? 0 nogil:
 
     cdef DTYPE_t u[3]
     cdef DTYPE_t ifu0[3]
@@ -733,7 +733,7 @@ cdef DTYPE_t C_line_of_sight_projection(DTYPE_t[:,:,:] density,
     cdef int jumper[1]
 
     cdef DTYPE_t (*integrator)(DTYPE_t[:,:,:],
-                               DTYPE_t u[3], DTYPE_t u0[3], int u_delta[3], int iu0[3], int jumper[1], DTYPE_t alpha_max) nogil
+                               DTYPE_t u[3], DTYPE_t u0[3], int u_delta[3], int iu0[3], int jumper[1], DTYPE_t alpha_max) noexcept nogil
 
     if integrator_id == 0:
       integrator = integrator0
diff --git a/setup.py b/setup.py
index ae7f560..29f97fd 100644
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,7 @@ extensions = [
     Extension(
         "sphereproj._project",
         sources=[
-            "ext_src/_project.pyx", "ext_src/_project.cpp"
+            "ext_src/_project.pyx"
         ],
         include_dirs=["ext_src"],
         language="c++"