3 files changed, 8 insertions, 1 deletions

diff --git a/Misc/ACKS b/Misc/ACKS
index ce010d51f2..dbb2035fac 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -771,3 +771,4 @@ Uwe Zessin
 Amaury Forgeot d'Arc
 Peter Åstrand
 Tarek ZiadŽ
+Victor Stinner
diff --git a/Misc/NEWS b/Misc/NEWS
index 010c06f4e6..3272f00b55 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -27,6 +27,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #3313: Fixed a crash when a failed dlopen() call does not set
+  a valid dlerror() message.
+
 - Issue #3258: Fixed a crash when a ctypes POINTER type to an
   incomplete structure was created.
 
diff --git a/Modules/_ctypes/callproc.c b/Modules/_ctypes/callproc.c
index 0a305ed89d..d45278580f 100644
--- a/Modules/_ctypes/callproc.c
+++ b/Modules/_ctypes/callproc.c
@@ -1383,8 +1383,11 @@ static PyObject *py_dl_open(PyObject *self, PyObject *args)
 	mode |= RTLD_NOW;
 	handle = ctypes_dlopen(name, mode);
 	if (!handle) {
+		char *errmsg = ctypes_dlerror();
+		if (!errmsg)
+			errmsg = "dlopen() error";
 		PyErr_SetString(PyExc_OSError,
-				       ctypes_dlerror());
+				       errmsg);
 		return NULL;
 	}
 	return PyLong_FromVoidPtr(handle);