diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index aa76fca..6da4e34 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -11,9 +11,10 @@ jobs:
     name: build (${{ matrix.python-version }}, ${{ matrix.os }})
     runs-on: ${{ matrix.os }}
     strategy:
+      fail-fast: false
       matrix:
         os: ["ubuntu-latest", "windows-latest"]
-        python-version: ["3.10"]
+        python-version: ["3.9", "3.10"]
     steps:
       - name: Checkout ibl-neuropixel repo
         uses: actions/checkout@v3
@@ -27,7 +28,7 @@ jobs:
 
       - name: flake8
         run: |
-          pip install flake8 --quiet
+          pip install flake8>=7 --quiet
           cd ibl-neuropixel
           python -m flake8
 
diff --git a/requirements.txt b/requirements.txt
index ce1cffc..fada42e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,7 +2,8 @@ iblutil >= 1.7.0
 joblib
 matplotlib
 mtscomp
-numpy
+numpy >= 1.21.6
 one-api
 pandas
-scipy
+scipy >= 1.11
+pyfftw
diff --git a/src/ibldsp/plots.py b/src/ibldsp/plots.py
index 2973d98..9ab2487 100644
--- a/src/ibldsp/plots.py
+++ b/src/ibldsp/plots.py
@@ -16,17 +16,17 @@ def show_channels_labels(raw, fs, channel_labels, xfeats):
     butt = scipy.signal.sosfiltfilt(sos_hp, raw)
     fig, ax = plt.subplots(1, 5, figsize=(18, 6), gridspec_kw={'width_ratios': [1, 1, 1, 8, .2]})
     ax[0].plot(xfeats['xcor_hf'], np.arange(nc))
-    ax[0].plot(xfeats['xcor_hf'][iko := channel_labels == 1], np.arange(nc)[iko], 'r*')
+    ax[0].plot(xfeats['xcor_hf'][(iko := channel_labels == 1)], np.arange(nc)[iko], 'r*')
     ax[0].plot([- .5, -.5], [0, nc], 'r--')
     ax[0].set(ylabel='channel #', xlabel='high coherence', ylim=[0, nc], title='a) dead channel')
     ax[1].plot(xfeats['psd_hf'], np.arange(nc))
-    ax[1].plot(xfeats['psd_hf'][iko := channel_labels == 2], np.arange(nc)[iko], 'r*')
+    ax[1].plot(xfeats['psd_hf'][(iko := channel_labels == 2)], np.arange(nc)[iko], 'r*')
     ax[1].plot([.02, .02], [0, nc], 'r--')
 
     ax[1].set(yticklabels=[], xlabel='PSD', ylim=[0, nc], title='b) noisy channel')
     ax[1].sharey(ax[0])
     ax[2].plot(xfeats['xcor_lf'], np.arange(nc))
-    ax[2].plot(xfeats['xcor_lf'][iko := channel_labels == 3], np.arange(nc)[iko], 'r*')
+    ax[2].plot(xfeats['xcor_lf'][(iko := channel_labels == 3)], np.arange(nc)[iko], 'r*')
     ax[2].plot([-.75, -.75], [0, nc], 'r--')
     ax[2].set(yticklabels=[], xlabel='low coherence', ylim=[0, nc], title='c) outside')
     ax[2].sharey(ax[0])