diff --git a/CHANGES.current b/CHANGES.current
index 937f9f871..7ce58028d 100644
--- a/CHANGES.current
+++ b/CHANGES.current
@@ -7,6 +7,14 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-03-26: eltoder
+            [Python] #1684 Use different capsule names with and without -builtin
+
+            Types generated with and without -builtin are not compatible. Mixing
+            them in a common type list leads to crashes. Avoid this by using
+            different capsule names: "type_pointer_capsule" without -builtin and
+            "type_pointer_capsule_builtin" with.
+
 2022-03-25: wsfulton
             The debug command line options that display parse tree nodes
             (-debug-module, -debug-top, -debug-symtabs) now display previously hidden
diff --git a/Examples/test-suite/common.mk b/Examples/test-suite/common.mk
index 48e0546c1..ddbb75d22 100644
--- a/Examples/test-suite/common.mk
+++ b/Examples/test-suite/common.mk
@@ -831,6 +831,13 @@ endif
 partialcheck:
 	$(MAKE) check CC=true CXX=true LDSHARED=true CXXSHARED=true RUNTOOL=true COMPILETOOL=true
 
+swig_and_compile_cpp_helper = \
+	$(MAKE) -f $(top_builddir)/$(EXAMPLES)/Makefile SRCDIR='$(SRCDIR)' CXXSRCS='$(CXXSRCS)' \
+	SWIG_LIB_DIR='$(SWIG_LIB_DIR)' SWIGEXE='$(SWIGEXE)' \
+	LIBS='$(LIBS)' INCLUDES='$(INCLUDES)' SWIGOPT=$(2) NOLINK=true \
+	TARGET="$(TARGETPREFIX)$(1)$(TARGETSUFFIX)" INTERFACEDIR='$(INTERFACEDIR)' INTERFACE="$(1).i" \
+	$(LANGUAGE)$(VARIANT)_cpp
+
 swig_and_compile_cpp =  \
 	$(MAKE) -f $(top_builddir)/$(EXAMPLES)/Makefile SRCDIR='$(SRCDIR)' CXXSRCS='$(CXXSRCS)' \
 	SWIG_LIB_DIR='$(SWIG_LIB_DIR)' SWIGEXE='$(SWIGEXE)' \
@@ -847,11 +854,7 @@ swig_and_compile_c =  \
 
 swig_and_compile_multi_cpp = \
 	for f in `cat $(top_srcdir)/$(EXAMPLES)/$(TEST_SUITE)/$*.list` ; do \
-	  $(MAKE) -f $(top_builddir)/$(EXAMPLES)/Makefile SRCDIR='$(SRCDIR)' CXXSRCS='$(CXXSRCS)' \
-	  SWIG_LIB_DIR='$(SWIG_LIB_DIR)' SWIGEXE='$(SWIGEXE)' \
-	  LIBS='$(LIBS)' INCLUDES='$(INCLUDES)' SWIGOPT='$(SWIGOPT)' NOLINK=true \
-	  TARGET="$(TARGETPREFIX)$${f}$(TARGETSUFFIX)" INTERFACEDIR='$(INTERFACEDIR)' INTERFACE="$$f.i" \
-	  $(LANGUAGE)$(VARIANT)_cpp; \
+	  $(call swig_and_compile_cpp_helper,$${f},'$(SWIGOPT)'); \
 	done
 
 swig_and_compile_external =  \
diff --git a/Examples/test-suite/python/Makefile.in b/Examples/test-suite/python/Makefile.in
index c232829f3..ccd5ca513 100644
--- a/Examples/test-suite/python/Makefile.in
+++ b/Examples/test-suite/python/Makefile.in
@@ -93,6 +93,9 @@ C_TEST_CASES += \
 	python_nondynamic \
 	python_varargs_typemap \
 
+MULTI_CPP_TEST_CASES += \
+	python_runtime_data \
+
 include $(srcdir)/../common.mk
 
 # Overridden variables here
@@ -102,6 +105,13 @@ VALGRIND_OPT += --suppressions=pythonswig.supp
 # Custom tests - tests with additional commandline options
 python_flatstaticmethod.cpptest: SWIGOPT += -flatstaticmethod
 
+# Make sure just python_runtime_data_builtin.i uses the -builtin option. Note: does not use python_runtime_data.list for all steps.
+python_runtime_data.multicpptest: override SWIG_FEATURES := $(filter-out -builtin,$(SWIG_FEATURES))
+python_runtime_data.multicpptest: override SWIGOPT := $(filter-out -builtin,$(SWIGOPT))
+python_runtime_data.multicpptest: swig_and_compile_multi_cpp = \
+	$(call swig_and_compile_cpp_helper,python_runtime_data_builtin,'$(SWIGOPT) -builtin') && \
+	$(call swig_and_compile_cpp_helper,python_runtime_data_nobuiltin,'$(SWIGOPT)')
+
 # Rules for the different types of tests
 %.cpptest:
 	$(setup)
@@ -149,7 +159,7 @@ clean:
 	rm -f hugemod.h hugemod_a.i hugemod_b.i hugemod_a.py hugemod_b.py hugemod_runme.py
 	rm -f imports_a.py imports_b.py mod_a.py mod_b.py multi_import_a.py
 	rm -f multi_import_b.py multi_import_d.py packageoption_a.py packageoption_b.py packageoption_c.py
-	rm -f template_typedef_cplx2.py
+	rm -f template_typedef_cplx2.py python_runtime_data_builtin.py python_runtime_data_nobuiltin.py
 
 hugemod_runme = hugemod$(SCRIPTPREFIX)
 
diff --git a/Examples/test-suite/python/python_runtime_data_runme.py b/Examples/test-suite/python/python_runtime_data_runme.py
new file mode 100644
index 000000000..063bf82d1
--- /dev/null
+++ b/Examples/test-suite/python/python_runtime_data_runme.py
@@ -0,0 +1,15 @@
+import python_runtime_data_builtin as builtin
+import python_runtime_data_nobuiltin as nobuiltin
+
+def swig_assert(a):
+    if not a:
+        raise RuntimeError("Failed")
+
+swig_assert(builtin.is_python_builtin())
+swig_assert(not nobuiltin.is_python_builtin())
+
+for i in range(1, 5):
+    v1 = builtin.vectord([1.] * i)
+    swig_assert(len(v1) == i)
+    v2 = nobuiltin.vectord([1.] * i)
+    swig_assert(len(v2) == i)
diff --git a/Examples/test-suite/python_runtime_data.list b/Examples/test-suite/python_runtime_data.list
new file mode 100644
index 000000000..e88ef0c3b
--- /dev/null
+++ b/Examples/test-suite/python_runtime_data.list
@@ -0,0 +1,2 @@
+python_runtime_data_builtin
+python_runtime_data_nobuiltin
diff --git a/Examples/test-suite/python_runtime_data_builtin.i b/Examples/test-suite/python_runtime_data_builtin.i
new file mode 100644
index 000000000..1001b837c
--- /dev/null
+++ b/Examples/test-suite/python_runtime_data_builtin.i
@@ -0,0 +1,15 @@
+// Test swig_runtime_data with and without -builtin
+
+%module python_runtime_data_builtin
+
+%inline %{
+#ifdef SWIGPYTHON_BUILTIN
+bool is_python_builtin() { return true; }
+#else
+bool is_python_builtin() { return false; }
+#endif
+%}
+
+%include std_vector.i
+
+%template(vectord) std::vector<double>;
diff --git a/Examples/test-suite/python_runtime_data_nobuiltin.i b/Examples/test-suite/python_runtime_data_nobuiltin.i
new file mode 100644
index 000000000..18c041468
--- /dev/null
+++ b/Examples/test-suite/python_runtime_data_nobuiltin.i
@@ -0,0 +1,3 @@
+%module python_runtime_data_nobuiltin
+
+%include "python_runtime_data_builtin.i"
diff --git a/Lib/python/pyhead.swg b/Lib/python/pyhead.swg
index 669990719..d3730a8fa 100644
--- a/Lib/python/pyhead.swg
+++ b/Lib/python/pyhead.swg
@@ -80,7 +80,12 @@ SWIG_Python_str_FromChar(const char *c)
 
 /* SWIGPY_USE_CAPSULE is no longer used within SWIG itself, but some user interface files check for it. */
 # define SWIGPY_USE_CAPSULE
-# define SWIGPY_CAPSULE_NAME ("swig_runtime_data" SWIG_RUNTIME_VERSION ".type_pointer_capsule" SWIG_TYPE_TABLE_NAME)
+#ifdef SWIGPYTHON_BUILTIN
+# define SWIGPY_CAPSULE_ATTR_NAME "type_pointer_capsule_builtin" SWIG_TYPE_TABLE_NAME
+#else
+# define SWIGPY_CAPSULE_ATTR_NAME "type_pointer_capsule" SWIG_TYPE_TABLE_NAME
+#endif
+# define SWIGPY_CAPSULE_NAME ("swig_runtime_data" SWIG_RUNTIME_VERSION "." SWIGPY_CAPSULE_ATTR_NAME)
 
 #if PY_VERSION_HEX < 0x03020000
 #define PyDescr_TYPE(x) (((PyDescrObject *)(x))->d_type)
diff --git a/Lib/python/pyrun.swg b/Lib/python/pyrun.swg
index 3d3443946..081bb2cde 100644
--- a/Lib/python/pyrun.swg
+++ b/Lib/python/pyrun.swg
@@ -1686,7 +1686,7 @@ SWIG_Python_SetModule(swig_module_info *swig_module) {
 #endif
   PyObject *pointer = PyCapsule_New((void *) swig_module, SWIGPY_CAPSULE_NAME, SWIG_Python_DestroyModule);
   if (pointer && module) {
-    if (PyModule_AddObject(module, "type_pointer_capsule" SWIG_TYPE_TABLE_NAME, pointer) == 0) {
+    if (PyModule_AddObject(module, SWIGPY_CAPSULE_ATTR_NAME, pointer) == 0) {
       Swig_Capsule_global = pointer;
     } else {
       Py_DECREF(pointer);
diff --git a/Source/Modules/python.cxx b/Source/Modules/python.cxx
index 964e7d425..b2e67ff10 100644
--- a/Source/Modules/python.cxx
+++ b/Source/Modules/python.cxx
@@ -4229,6 +4229,9 @@ public:
     printSlot(f, getSlot(n, "feature:python:am_await"), "am_await", "unaryfunc");
     printSlot(f, getSlot(n, "feature:python:am_aiter"), "am_aiter", "unaryfunc");
     printSlot(f, getSlot(n, "feature:python:am_anext"), "am_anext", "unaryfunc");
+    Printv(f, "# if PY_VERSION_HEX >= 0x030a0000\n", NIL);
+    printSlot(f, getSlot(n, "feature:python:am_send"), "am_send", "sendfunc");
+    Printv(f, "# endif\n", NIL);
     Printf(f, "  },\n");
     Printv(f, "#endif\n", NIL);