GeezerVison

diff --git a/meson.build b/meson.build
index 7e941db..150e9f6 100644
--- a/meson.build
+++ b/meson.build
@@ -22,6 +22,9 @@ endif
 # flint.pc was missing -lflint until Flint 3.1.0
 if flint_dep.version().version_compare('<3.1')
   flint_dep = cc.find_library('flint')
+  have_acb_theta = true
+else
+  have_acb_theta = false
 endif
 
 pyflint_deps = [dep_py, gmp_dep, mpfr_dep, flint_dep]
diff --git a/src/flint/types/acb_mat.pyx b/src/flint/types/acb_mat.pyx
index 533bdc7..fff3531 100644
--- a/src/flint/types/acb_mat.pyx
+++ b/src/flint/types/acb_mat.pyx
@@ -20,6 +20,11 @@ from flint.flintlib.arf cimport *
 from flint.flintlib.acb cimport *
 from flint.flintlib.acb_mat cimport *
 
+try:
+    from .acb_theta import acb_mat_theta
+except ImportError:
+    acb_mat_theta = None
+
 cimport cython
 
 cdef acb_mat_coerce_operands(x, y):
@@ -814,3 +819,8 @@ cdef class acb_mat(flint_mat):
         if left:
             return Elist, L
         return Elist, R
+
+   def theta(tau, z, square=False):
+       if acb_mat_theta is None:
+           raise NotImplementedError("acb.theta() needs Flint >= 3.1.0")
+       ...
diff --git a/src/flint/types/meson.build b/src/flint/types/meson.build
index bf8caec..4fd6362 100644
--- a/src/flint/types/meson.build
+++ b/src/flint/types/meson.build
@@ -41,6 +41,10 @@ exts = [
   'fmpz_mpoly',
 ]
 
+if have_acb_theta
+  exts = exts + ['acb_theta']
+endif
+
 py.install_sources(
   pyfiles,
   pure: false,

pip install -r requirements-dev.txt
spin install

pip install --no-build-isolation --editable .

>>> import flint

$ python -m flint.test