diff --git a/docs/requirements.txt b/docs/requirements.txt
index 974cccd..b513c16 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,5 +1,5 @@
 PyYAML==6.0.1
-requests==2.31.0
+requests==2.32.3
 sphinx==7.2.6
 sphinx-carousel==1.2.0
 sphinx-copybutton==0.5.2
diff --git a/pyproject.toml b/pyproject.toml
index 23d07cc..aa5045d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -21,7 +21,7 @@ classifiers = [
 dependencies = [
     "cycler>=0.12.1",
     "matplotlib>=3.7.0",
-    "numpy>=1.22.0",
+    "numpy>=1.22.0,<=2.1.1",
     "scikit-image>=0.22.0",
     "scipy>=1.11.0",
     "shapely>=2.0.0",
diff --git a/stnmf/plot.py b/stnmf/plot.py
index 5bc8b85..734c0fb 100644
--- a/stnmf/plot.py
+++ b/stnmf/plot.py
@@ -375,7 +375,7 @@ def weights(w, m, colors=default_color, ax=None, yticks=True, **kwargs):
              plt.rcParams['font.family'])
     ax.grid(axis='y', color='lightgray')
     ax.get_ygridlines()[0].set_xdata((0.05, 1))
-    margin = w.ptp() * 0.1
+    margin = np.ptp(w) * 0.1
     ax.set_ylim(min(w.min(), 0) - margin, max(w.max(), 0) + margin)
 
 
diff --git a/stnmf/preprocessing/spiketriggered.py b/stnmf/preprocessing/spiketriggered.py
index 3851351..ef6372e 100644
--- a/stnmf/preprocessing/spiketriggered.py
+++ b/stnmf/preprocessing/spiketriggered.py
@@ -344,7 +344,7 @@ def stimulusensemble(stimulus, spikes, sta_temp, continuous=False,
         ind = np.nonzero(sp)[0]
         for i in ind:
             np.dot(stim[..., i:i+tau], sta_temp, out=sts[..., 0])
-            num_sp = sp[i, 0]
+            num_sp = int(sp[i, 0])
             np.copyto(ste[..., s_ind:s_ind+num_sp], sts)
             s_ind += num_sp