diff --git a/src/cortecs/fit/fit.py b/src/cortecs/fit/fit.py
index f8b8cdc..62301df 100644
--- a/src/cortecs/fit/fit.py
+++ b/src/cortecs/fit/fit.py
@@ -1,7 +1,6 @@
 """
 The high-level API for fitting. Requires the Opac object.
 """
-
 import warnings
 from functools import partial
 from multiprocessing import Pool
@@ -138,8 +137,15 @@ def fit_parallel(self):
         :return:
         """
         with warnings.catch_warnings():
-            num_processes = 3
-            func = partial(self.func_fit, self.P, self.T, **self.fitter_kwargs)
+            num_processes = 1
+
+            func = partial(
+                self.fit_func,
+                P=self.P,
+                T=self.T,
+                prep_res=self.prep_res,
+                **self.fitter_kwargs
+            )
 
             self.pbar = tqdm(
                 total=len(self.wl),
@@ -150,18 +156,36 @@ def fit_parallel(self):
             )
 
             # these two lines are where the bulk of the multiprocessing happens
-            p = Pool(num_processes)
-
-            for i in range(len(self.wl)):
-                p.apply_async(
-                    func,
-                    args=(self.Opac.cross_section[:, :, i],),
-                    callback=self.update_pbar,
+            pool = Pool(num_processes)
+
+            # actualy loop over using pool.map. need
+            # reformat the cross_section to be a list of 2D arrays
+            cross_section_reformatted = [
+                self.opac.cross_section[:, :, i] for i in range(len(self.wl))
+            ]
+
+            # we tehcnically want sorted results. but apply async is the only way to get the progress bar to work!
+            async_result = []
+            for i, item in enumerate(cross_section_reformatted):
+                async_result.append(
+                    [i, pool.apply_async(func, args=(item,), callback=self.update_pbar)]
                 )
-            p.close()
-            p.join()
+
+            # Close the pool
+            pool.close()
+            pool.join()
+
+            # Close the progress bar
             self.pbar.close()
 
+            # sort the results based on the index
+            sorted_results = [None] * len(async_result)
+            for item in async_result:
+                i, res = item
+                sorted_results[i] = res.get()
+
+        self.fitter_results = [self.prep_res, sorted_results]
+
         return
 
     def save(self, savename):
diff --git a/src/cortecs/fit/fit_pca.py b/src/cortecs/fit/fit_pca.py
index 4e3076b..93eaaaf 100644
--- a/src/cortecs/fit/fit_pca.py
+++ b/src/cortecs/fit/fit_pca.py
@@ -104,7 +104,7 @@ def do_pca(cube, nc=3):
     return xMat, standardized_cube, s, vh, u
 
 
-def fit_pca(cross_section, P, T, xMat, fit_axis="pressure", **kwargs):
+def fit_pca(cross_section, P, T, prep_res, fit_axis="pressure", **kwargs):
     """
     Fits the PCA to the opacity data.
 
@@ -120,7 +120,7 @@ def fit_pca(cross_section, P, T, xMat, fit_axis="pressure", **kwargs):
         :beta: (nc x pixels) PCA coefficients
     """
     # print("shapes for everything:", cross_section.shape, P.shape, T.shape, xMat.shape)
-
+    xMat = prep_res
     cross_section = move_cross_section_axis(cross_section, fit_axis)
     beta = fit_mlr(cross_section, xMat)
     return beta
diff --git a/src/cortecs/tests/test_fit.py b/src/cortecs/tests/test_fit.py
index 220b23b..edd52fd 100644
--- a/src/cortecs/tests/test_fit.py
+++ b/src/cortecs/tests/test_fit.py
@@ -103,3 +103,39 @@ def test_nan_pca_cube_errors(self):
             do_pca,
             bad_cube,
         )
+
+    def test_fit_parallel_zero_arg(self):
+        """
+        I want to make sure that the parallel fitting function works.
+        :return:
+        """
+        fitter_parallel = Fitter(self.opac, method="pca")
+        fitter_parallel.fit(parallel=True)
+
+        # check against serial
+        fitter_serial = Fitter(self.opac, method="pca")
+        fitter_serial.fit(parallel=False)
+
+        # are they the same?
+
+        np.testing.assert_almost_equal(
+            fitter_parallel.fitter_results[0], fitter_serial.fitter_results[0]
+        )
+
+    def test_fit_parallel_first_arg(self):
+        """
+        I want to make sure that the parallel fitting function works.
+        :return:
+        """
+        fitter_parallel = Fitter(self.opac, method="pca")
+        fitter_parallel.fit(parallel=True)
+
+        # check against serial
+        fitter_serial = Fitter(self.opac, method="pca")
+        fitter_serial.fit(parallel=False)
+
+        # are they the same?
+
+        np.testing.assert_almost_equal(
+            fitter_parallel.fitter_results[1], fitter_serial.fitter_results[1]
+        )