diff --git a/CHANGELOG.md b/CHANGELOG.md
index f33840b0596..9b1219cd09e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 - Change `PyErr::fetch()` to return `Option<PyErr>`. [#1717](https://github.com/PyO3/pyo3/pull/1717)
 
+### Fixed
+
+- Restrict FFI definitions `PyGILState_Check` and `Py_tracefunc` to the unlimited API. [#1787](https://github.com/PyO3/pyo3/pull/1787)
+
 ## [0.14.2] - 2021-08-09
 
 ### Added
diff --git a/src/ffi/cpython/ceval.rs b/src/ffi/cpython/ceval.rs
index 13173b1b146..29affbd72bb 100644
--- a/src/ffi/cpython/ceval.rs
+++ b/src/ffi/cpython/ceval.rs
@@ -1,5 +1,4 @@
-use crate::ffi::object::{freefunc, PyObject};
-use crate::ffi::pystate::Py_tracefunc;
+use crate::ffi::{freefunc, PyObject, Py_tracefunc};
 use std::os::raw::c_int;
 
 extern "C" {
diff --git a/src/ffi/cpython/mod.rs b/src/ffi/cpython/mod.rs
index 7e8c9c6aec0..19f3ccd12f1 100644
--- a/src/ffi/cpython/mod.rs
+++ b/src/ffi/cpython/mod.rs
@@ -2,6 +2,7 @@ pub(crate) mod abstract_;
 // skipped bytearrayobject.h
 #[cfg(not(PyPy))]
 pub(crate) mod bytesobject;
+#[cfg(not(PyPy))]
 pub(crate) mod ceval;
 pub(crate) mod code;
 pub(crate) mod compile;
@@ -18,13 +19,12 @@ pub(crate) mod object;
 pub(crate) mod pydebug;
 #[cfg(all(Py_3_8, not(PyPy)))]
 pub(crate) mod pylifecycle;
-
-#[cfg(all(Py_3_8, not(PyPy)))]
 pub(crate) mod pystate;
 
 pub use self::abstract_::*;
 #[cfg(not(PyPy))]
 pub use self::bytesobject::*;
+#[cfg(not(PyPy))]
 pub use self::ceval::*;
 pub use self::code::*;
 pub use self::compile::*;
@@ -39,6 +39,4 @@ pub use self::object::*;
 pub use self::pydebug::*;
 #[cfg(all(Py_3_8, not(PyPy)))]
 pub use self::pylifecycle::*;
-
-#[cfg(all(Py_3_8, not(PyPy)))]
 pub use self::pystate::*;
diff --git a/src/ffi/cpython/pystate.rs b/src/ffi/cpython/pystate.rs
index 38491baeb31..1564815dd59 100644
--- a/src/ffi/cpython/pystate.rs
+++ b/src/ffi/cpython/pystate.rs
@@ -1,7 +1,19 @@
-use crate::ffi::pystate::{PyInterpreterState, PyThreadState};
+#[cfg(not(PyPy))]
+use crate::ffi::PyThreadState;
+use crate::ffi::{PyFrameObject, PyInterpreterState, PyObject};
 use std::os::raw::c_int;
 
-// Py_tracefunc is defined in ffi::pystate
+// skipped _PyInterpreterState_RequiresIDRef
+// skipped _PyInterpreterState_RequireIDRef
+
+// skipped _PyInterpreterState_GetMainModule
+
+pub type Py_tracefunc = extern "C" fn(
+    obj: *mut PyObject,
+    frame: *mut PyFrameObject,
+    what: c_int,
+    arg: *mut PyObject,
+) -> c_int;
 
 pub const PyTrace_CALL: c_int = 0;
 pub const PyTrace_EXCEPTION: c_int = 1;
@@ -12,13 +24,38 @@ pub const PyTrace_C_EXCEPTION: c_int = 5;
 pub const PyTrace_C_RETURN: c_int = 6;
 pub const PyTrace_OPCODE: c_int = 7;
 
+// skipped PyTraceInfo
+// skipped CFrame
+// skipped _PyErr_StackItem
+// skipped _PyStackChunk
+// skipped _ts (aka PyThreadState)
+
 extern "C" {
-    // PyGILState_Check is defined in ffi::pystate
+    // skipped _PyThreadState_Prealloc
+    // skipped _PyThreadState_UncheckedGet
+    // skipped _PyThreadState_GetDict
+
+    #[cfg_attr(PyPy, link_name = "_PyPyGILState_Check")]
+    pub fn PyGILState_Check() -> c_int;
+
+    // skipped _PyGILState_GetInterpreterStateUnsafe
+    // skipped _PyThread_CurrentFrames
+    // skipped _PyThread_CurrentExceptions
+
+    #[cfg(not(PyPy))]
+    #[cfg_attr(docsrs, doc(cfg(not(PyPy))))]
     pub fn PyInterpreterState_Main() -> *mut PyInterpreterState;
+    #[cfg_attr(PyPy, link_name = "_PyPyInterpreterState_Head")]
     pub fn PyInterpreterState_Head() -> *mut PyInterpreterState;
+    #[cfg_attr(PyPy, link_name = "_PyPyInterpreterState_Next")]
     pub fn PyInterpreterState_Next(interp: *mut PyInterpreterState) -> *mut PyInterpreterState;
+    #[cfg(not(PyPy))]
+    #[cfg_attr(docsrs, doc(cfg(not(PyPy))))]
     pub fn PyInterpreterState_ThreadHead(interp: *mut PyInterpreterState) -> *mut PyThreadState;
+    #[cfg(not(PyPy))]
+    #[cfg_attr(docsrs, doc(cfg(not(PyPy))))]
     pub fn PyThreadState_Next(tstate: *mut PyThreadState) -> *mut PyThreadState;
+    // skipped PyThreadState_DeleteCurrent
 }
 
 #[cfg(Py_3_9)]
@@ -44,3 +81,17 @@ extern "C" {
         eval_frame: _PyFrameEvalFunction,
     );
 }
+
+// skipped _PyInterpreterState_GetConfig
+// skipped _PyInterpreterState_GetConfigCopy
+// skipped _PyInterpreterState_SetConfig
+// skipped _Py_GetConfig
+
+// skipped _PyCrossInterpreterData
+// skipped _PyObject_GetCrossInterpreterData
+// skipped _PyCrossInterpreterData_NewObject
+// skipped _PyCrossInterpreterData_Release
+// skipped _PyObject_CheckCrossInterpreterData
+// skipped crossinterpdatafunc
+// skipped _PyCrossInterpreterData_RegisterClass
+// skipped _PyCrossInterpreterData_Lookup
diff --git a/src/ffi/pystate.rs b/src/ffi/pystate.rs
index 81631851e6b..e26619e7ec8 100644
--- a/src/ffi/pystate.rs
+++ b/src/ffi/pystate.rs
@@ -1,26 +1,49 @@
+#[cfg(not(PyPy))]
 use crate::ffi::moduleobject::PyModuleDef;
 use crate::ffi::object::PyObject;
-use crate::ffi::PyFrameObject;
-use std::os::raw::{c_int, c_long};
+use std::os::raw::c_int;
+#[cfg(not(PyPy))]
+use std::os::raw::c_long;
 
 pub const MAX_CO_EXTRA_USERS: c_int = 255;
 
+opaque_struct!(PyThreadState);
 opaque_struct!(PyInterpreterState);
 
-#[repr(C)]
-#[derive(Copy, Clone)]
-pub struct PyThreadState {
-    pub ob_base: PyObject,
-    pub interp: *mut PyInterpreterState,
-}
-
 extern "C" {
+    #[cfg(not(PyPy))]
+    #[cfg_attr(docsrs, doc(cfg(not(PyPy))))]
     pub fn PyInterpreterState_New() -> *mut PyInterpreterState;
+    #[cfg(not(PyPy))]
+    #[cfg_attr(docsrs, doc(cfg(not(PyPy))))]
     pub fn PyInterpreterState_Clear(arg1: *mut PyInterpreterState);
+    #[cfg(not(PyPy))]
+    #[cfg_attr(docsrs, doc(cfg(not(PyPy))))]
     pub fn PyInterpreterState_Delete(arg1: *mut PyInterpreterState);
-    //fn _PyState_AddModule(arg1: *mut PyObject,
-    //                      arg2: *mut PyModuleDef) -> c_int;
+
+    #[cfg(all(Py_3_9, not(PyPy)))]
+    #[cfg_attr(docsrs, doc(all(Py_3_9, not(PyPy))))]
+    pub fn PyInterpreterState_Get() -> *mut PyInterpreterState;
+
+    #[cfg(all(Py_3_8, not(PyPy)))]
+    #[cfg_attr(docsrs, doc(all(Py_3_8, not(PyPy))))]
+    pub fn PyInterpreterState_GetDict() -> *mut PyObject;
+
+    #[cfg(all(Py_3_7, not(PyPy)))]
+    #[cfg_attr(docsrs, doc(all(Py_3_7, not(PyPy))))]
+    pub fn PyInterpreterState_GetID() -> i64;
+
+    #[cfg(not(PyPy))]
+    #[cfg_attr(docsrs, doc(cfg(not(PyPy))))]
+    pub fn PyState_AddModule(arg1: *mut PyObject, arg2: *mut PyModuleDef) -> c_int;
+    #[cfg(not(PyPy))]
+    #[cfg_attr(docsrs, doc(cfg(not(PyPy))))]
+    pub fn PyState_RemoveModule(arg1: *mut PyModuleDef) -> c_int;
+
+    #[cfg(not(PyPy))]
+    #[cfg_attr(docsrs, doc(cfg(not(PyPy))))]
     pub fn PyState_FindModule(arg1: *mut PyModuleDef) -> *mut PyObject;
+
     #[cfg_attr(PyPy, link_name = "PyPyThreadState_New")]
     pub fn PyThreadState_New(arg1: *mut PyInterpreterState) -> *mut PyThreadState;
     //fn _PyThreadState_Prealloc(arg1: *mut PyInterpreterState)
@@ -39,6 +62,8 @@ extern "C" {
     pub fn PyThreadState_Swap(arg1: *mut PyThreadState) -> *mut PyThreadState;
     #[cfg_attr(PyPy, link_name = "PyPyThreadState_GetDict")]
     pub fn PyThreadState_GetDict() -> *mut PyObject;
+    #[cfg(not(PyPy))]
+    #[cfg_attr(docsrs, doc(cfg(not(PyPy))))]
     pub fn PyThreadState_SetAsyncExc(arg1: c_long, arg2: *mut PyObject) -> c_int;
 }
 
@@ -54,18 +79,12 @@ extern "C" {
     pub fn PyGILState_Ensure() -> PyGILState_STATE;
     #[cfg_attr(PyPy, link_name = "PyPyGILState_Release")]
     pub fn PyGILState_Release(arg1: PyGILState_STATE);
+    #[cfg(not(PyPy))]
+    #[cfg_attr(docsrs, doc(cfg(not(PyPy))))]
     pub fn PyGILState_GetThisThreadState() -> *mut PyThreadState;
-    pub fn PyGILState_Check() -> c_int;
 }
 
 #[inline]
 pub unsafe fn PyThreadState_GET() -> *mut PyThreadState {
     PyThreadState_Get()
 }
-
-pub type Py_tracefunc = extern "C" fn(
-    obj: *mut PyObject,
-    frame: *mut PyFrameObject,
-    what: c_int,
-    arg: *mut PyObject,
-) -> c_int;