diff --git a/src/_imaging.c b/src/_imaging.c
index 0888188fb20..8921e809f6b 100644
--- a/src/_imaging.c
+++ b/src/_imaging.c
@@ -929,6 +929,9 @@ static PyObject *
 _convert_matrix(ImagingObject *self, PyObject *args) {
     char *mode;
     float m[12];
+    Imaging imOut;
+    ImagingSectionCookie cookie;
+
     if (!PyArg_ParseTuple(args, "s(ffff)", &mode, m + 0, m + 1, m + 2, m + 3)) {
         PyErr_Clear();
         if (!PyArg_ParseTuple(
@@ -950,8 +953,10 @@ _convert_matrix(ImagingObject *self, PyObject *args) {
             return NULL;
         }
     }
-
-    return PyImagingNew(ImagingConvertMatrix(self->image, mode, m));
+    ImagingSectionEnter(&cookie);
+    imOut = ImagingConvertMatrix(self->image, mode, m);
+    ImagingSectionLeave(&cookie);
+    return PyImagingNew(imOut);
 }
 
 static PyObject *