diff --git a/pyproject.toml b/pyproject.toml
index 738f92346..598b6081d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -71,7 +71,7 @@ tutorials = [
 # Full feature set (everything except dev tools)
 full = [
     "tsam_xarray >= 0.6.5, < 1",  # Time series aggregation for clustering (wraps tsam); 0.6.5 renames cluster_weights to cluster_counts
-    "tsam >= 3.4.0, < 4",  # Directly imported for ClusterConfig, ExtremeConfig, SegmentConfig
+    "tsam >= 3.4.0, < 5",  # Directly imported for ClusterConfig, ExtremeConfig, SegmentConfig
     "pyvis==0.3.2",  # Visualizing FlowSystem Network
     "scipy >= 1.15.1, < 2", # Used by tsam. Prior versions have conflict with highspy. See https://github.com/scipy/scipy/issues/22257
     "gurobipy >= 10.0.0, < 14; python_version < '3.14'",  # No Python 3.14 wheels yet (expected Q1 2026)
@@ -88,7 +88,7 @@ full = [
 dev = [
     "xarray<2026.8",  # TODO: drop once linopy ships xarray 2026.3+ compat fix
     "tsam_xarray==0.6.6",  # Time series aggregation for clustering (wraps tsam)
-    "tsam==3.4.0",  # Directly imported for ClusterConfig, ExtremeConfig, SegmentConfig
+    "tsam==4.0.0",  # Directly imported for ClusterConfig, ExtremeConfig, SegmentConfig
     "pytest==9.1.1",
     "pytest-xdist==3.8.0",
     "nbformat==5.11.0",