diff --git a/lib/libcfitsio.a b/lib/libcfitsio.a
deleted file mode 100644
index 6d79f323..00000000
Binary files a/lib/libcfitsio.a and /dev/null differ
diff --git a/src/kbmod/search/image_stack.cpp b/src/kbmod/search/image_stack.cpp
index ea64ce36..c8e13b5b 100644
--- a/src/kbmod/search/image_stack.cpp
+++ b/src/kbmod/search/image_stack.cpp
@@ -144,33 +144,6 @@ void ImageStack::clear_from_gpu() {
     data_on_gpu = false;
 }
 
-RawImage ImageStack::make_global_mask(int flags, int threshold) {
-    uint64_t npixels = get_npixels();
-
-    // Start with an empty global mask.
-    RawImage global_mask = RawImage(width, height);
-    global_mask.set_all(0.0);
-
-    // For each pixel count the number of images where it is masked.
-    std::vector<int> counts(npixels, 0);
-    for (unsigned int img = 0; img < images.size(); ++img) {
-        auto imgMask = images[img].get_mask().get_image().reshaped();
-
-        // Count the number of times a pixel has any of the given flags
-        for (uint64_t pixel = 0; pixel < npixels; ++pixel) {
-            if ((flags & static_cast<int>(imgMask[pixel])) != 0) counts[pixel]++;
-        }
-    }
-
-    // Set all pixels below threshold to 0 and all above to 1
-    auto global_m = global_mask.get_image().reshaped();
-    for (uint64_t p = 0; p < npixels; ++p) {
-        global_m[p] = counts[p] < threshold ? 0.0 : 1.0;
-    }
-
-    return global_mask;
-}
-
 #ifdef Py_PYTHON_H
 static void image_stack_bindings(py::module& m) {
     using is = search::ImageStack;
@@ -194,7 +167,6 @@ static void image_stack_bindings(py::module& m) {
             .def("build_zeroed_times", &is::build_zeroed_times, pydocs::DOC_ImageStack_build_zeroed_times)
             .def("sort_by_time", &is::sort_by_time, pydocs::DOC_ImageStack_sort_by_time)
             .def("img_count", &is::img_count, pydocs::DOC_ImageStack_img_count)
-            .def("make_global_mask", &is::make_global_mask, pydocs::DOC_ImageStack_make_global_mask)
             .def("convolve_psf", &is::convolve_psf, pydocs::DOC_ImageStack_convolve_psf)
             .def("get_width", &is::get_width, pydocs::DOC_ImageStack_get_width)
             .def("get_height", &is::get_height, pydocs::DOC_ImageStack_get_height)
diff --git a/src/kbmod/search/image_stack.h b/src/kbmod/search/image_stack.h
index 20c59abc..0eb5310d 100644
--- a/src/kbmod/search/image_stack.h
+++ b/src/kbmod/search/image_stack.h
@@ -47,9 +47,6 @@ class ImageStack {
 
     void convolve_psf();
 
-    // Make and return a global mask.
-    RawImage make_global_mask(int flags, int threshold);
-
     virtual ~ImageStack();
 
     // Functions to handle transfering data to/from GPU.
diff --git a/src/kbmod/search/pydocs/image_stack_docs.h b/src/kbmod/search/pydocs/image_stack_docs.h
index b6f8344e..a500175c 100644
--- a/src/kbmod/search/pydocs/image_stack_docs.h
+++ b/src/kbmod/search/pydocs/image_stack_docs.h
@@ -130,27 +130,6 @@ static const auto DOC_ImageStack_sort_by_time = R"doc(
   Raises a ``RuntimeError`` if the input image is the data is currently on GPU.    
   )doc";
 
-static const auto DOC_ImageStack_make_global_mask = R"doc(
-  Create a new global mask from a set of flags and a threshold.
-  The global mask marks a pixel as masked if and only if it is masked
-  by one of the given flags in at least ``threshold`` individual images.
-  The returned mask is binary.
-
-  Parameters
-  ----------
-  flags : `int`
-      A bit mask of mask flags to use when counting.
-  threshold : `int`
-      The minimum number of images in which a pixel must be masked to be
-      part of the global mask.
-
-  Returns
-  -------
-  global_mask : `RawImage`
-      A RawImage containing the global mask with 1 for masked pixels
-      and 0 for unmasked pixels.
-  )doc";
-
 static const auto DOC_ImageStack_convolve_psf = R"doc(
   Convolves each image (science and variance layers) with the PSF
   stored in the LayeredImage object.
diff --git a/tests/test_image_stack.py b/tests/test_image_stack.py
index a3eb346d..6ccade16 100644
--- a/tests/test_image_stack.py
+++ b/tests/test_image_stack.py
@@ -98,23 +98,6 @@ def test_times(self):
         for i in range(self.num_images):
             self.assertEqual(times[i], 2.0 * i)
 
-    def test_make_global_mask(self):
-        # Mask a single point in each image with flag=2.
-        for i in range(self.num_images):
-            self.images[i].get_mask().set_pixel(5, 5, 2)
-
-        # Apply the global mask for flag=1 and a threshold of the bit set
-        # in at least one mask. Note this ignores flag=2 for the count.
-        mask = self.im_stack.make_global_mask(1, 1)
-
-        # Check that the correct pixels are masked
-        for y in range(self.im_stack.get_height()):
-            for x in range(self.im_stack.get_width()):
-                if y == 10 and x >= 10 and x <= 10 + (self.num_images - 1):
-                    self.assertEqual(mask.get_pixel(y, x), 1)
-                else:
-                    self.assertEqual(mask.get_pixel(y, x), 0)
-
     # WOW, this is the first test that caught the fact that interpolated_add
     # called add, and that add had flipped i and j by accident. The first one.
     # TODO: more clean understandable tests for basic functionality, these big