diff --git a/src/ffi/sliceobject.rs b/src/ffi/sliceobject.rs
index b8a557ce..fa73102d 100644
--- a/src/ffi/sliceobject.rs
+++ b/src/ffi/sliceobject.rs
@@ -12,6 +12,15 @@ pub unsafe fn Py_Ellipsis() -> *mut PyObject {
     &mut _Py_EllipsisObject
 }
 
+#[cfg(not(Py_LIMITED_API))]
+#[repr(C)]
+pub struct PySliceObject {
+    pub ob_base: PyObject,
+    pub start: *mut PyObject,
+    pub stop: *mut PyObject,
+    pub step: *mut PyObject,
+}
+
 #[cfg_attr(windows, link(name = "pythonXY"))]
 extern "C" {
     #[cfg_attr(PyPy, link_name = "PyPySlice_Type")]
@@ -24,14 +33,6 @@ pub unsafe fn PySlice_Check(op: *mut PyObject) -> c_int {
     (Py_TYPE(op) == &mut PySlice_Type) as c_int
 }
 
-#[repr(C)]
-pub struct PySliceObject {
-    pub ob_base: PyObject,
-    pub start: *mut PyObject,
-    pub stop: *mut PyObject,
-    pub step: *mut PyObject,
-}
-
 extern "C" {
     #[cfg_attr(PyPy, link_name = "PyPySlice_New")]
     pub fn PySlice_New(
@@ -39,6 +40,10 @@ extern "C" {
         stop: *mut PyObject,
         step: *mut PyObject,
     ) -> *mut PyObject;
+
+    // skipped non-limited _PySlice_FromIndices
+    // skipped non-limited _PySlice_GetLongIndices
+
     #[cfg_attr(PyPy, link_name = "PyPySlice_GetIndices")]
     pub fn PySlice_GetIndices(
         r: *mut PyObject,
@@ -47,6 +52,8 @@ extern "C" {
         stop: *mut Py_ssize_t,
         step: *mut Py_ssize_t,
     ) -> c_int;
+
+    #[cfg(not(Py_3_7))]
     #[cfg_attr(PyPy, link_name = "PyPySlice_GetIndicesEx")]
     pub fn PySlice_GetIndicesEx(
         r: *mut PyObject,
@@ -57,3 +64,39 @@ extern "C" {
         slicelength: *mut Py_ssize_t,
     ) -> c_int;
 }
+
+#[cfg(Py_3_7)]
+#[inline]
+pub unsafe fn PySlice_GetIndicesEx(
+    slice: *mut PyObject,
+    length: Py_ssize_t,
+    start: *mut Py_ssize_t,
+    stop: *mut Py_ssize_t,
+    step: *mut Py_ssize_t,
+    slicelength: *mut Py_ssize_t,
+) -> c_int {
+    if PySlice_Unpack(slice, start, stop, step) < 0 {
+        *slicelength = 0;
+        -1
+    } else {
+        *slicelength = PySlice_AdjustIndices(length, start, stop, *step);
+        0
+    }
+}
+
+extern "C" {
+    #[cfg_attr(PyPy, link_name = "PyPySlice_Unpack")]
+    pub fn PySlice_Unpack(
+        slice: *mut PyObject,
+        start: *mut Py_ssize_t,
+        stop: *mut Py_ssize_t,
+        step: *mut Py_ssize_t,
+    ) -> c_int;
+
+    pub fn PySlice_AdjustIndices(
+        length: Py_ssize_t,
+        start: *mut Py_ssize_t,
+        stop: *mut Py_ssize_t,
+        step: Py_ssize_t,
+    ) -> Py_ssize_t;
+}