diff --git a/crates/solverforge-config/src/acceptor.rs b/crates/solverforge-config/src/acceptor.rs
index cd90871b..485a44a9 100644
--- a/crates/solverforge-config/src/acceptor.rs
+++ b/crates/solverforge-config/src/acceptor.rs
@@ -31,7 +31,7 @@ pub enum AcceptorConfig {
 #[serde(rename_all = "snake_case", deny_unknown_fields)]
 pub struct StepCountingHillClimbingConfig {
     /// Steps a non-improving move is accepted for after the last improvement.
-    /// Omitted: `100`.
+    /// Omitted: `100`. Explicit `0` is invalid.
     pub step_count_limit: Option<u64>,
 }
 
@@ -76,7 +76,8 @@ pub struct SimulatedAnnealingConfig {
     /// Hard-regression policy. Omitted: `temperature_controlled`.
     pub hard_regression_policy: Option<HardRegressionPolicyConfig>,
 
-    /// Sampled auto-calibration settings used when level_temperatures is omitted.
+    /// Sampled auto-calibration settings used when `level_temperatures` is
+    /// omitted. Setting both is invalid.
     pub calibration: Option<SimulatedAnnealingCalibrationConfig>,
 }
 
@@ -129,6 +130,6 @@ pub struct DiversifiedLateAcceptanceConfig {
 #[serde(rename_all = "snake_case", deny_unknown_fields)]
 pub struct GreatDelugeConfig {
     /// Fraction of the initial score's magnitude the water level rises per
-    /// step. Omitted: `0.001`.
+    /// step. Omitted: `0.001`. Must be finite and greater than 0.
     pub water_level_increase_ratio: Option<f64>,
 }
diff --git a/crates/solverforge-solver/src/builder/acceptor/tests.rs b/crates/solverforge-solver/src/builder/acceptor/tests.rs
index 51691fe0..5527b853 100644
--- a/crates/solverforge-solver/src/builder/acceptor/tests.rs
+++ b/crates/solverforge-solver/src/builder/acceptor/tests.rs
@@ -2,9 +2,9 @@ use super::*;
 use crate::builder::local_search_policy::CompiledAcceptor;
 use crate::builder::local_search_policy::ConfigValueError;
 use solverforge_config::{
-    AcceptorConfig, DiversifiedLateAcceptanceConfig, HardRegressionPolicyConfig,
+    AcceptorConfig, DiversifiedLateAcceptanceConfig, GreatDelugeConfig, HardRegressionPolicyConfig,
     LateAcceptanceConfig, SimulatedAnnealingCalibrationConfig, SimulatedAnnealingConfig,
-    TabuSearchConfig,
+    StepCountingHillClimbingConfig, TabuSearchConfig,
 };
 use solverforge_core::score::{HardSoftScore, SoftScore};
 use std::any::Any;
@@ -297,3 +297,47 @@ fn test_acceptor_builder_late_acceptance_rejects_zero_size() {
         );
     }
 }
+
+#[test]
+fn step_counting_hill_climbing_rejects_a_zero_step_count_limit() {
+    let config = AcceptorConfig::StepCountingHillClimbing(StepCountingHillClimbingConfig {
+        step_count_limit: Some(0),
+    });
+    let error = build_acceptor::<TestSolution>(&config).expect_err("zero is rejected");
+    assert_eq!(error.field(), "step_count_limit");
+    assert_eq!(error.message(), "must be greater than 0");
+
+    let config = AcceptorConfig::StepCountingHillClimbing(StepCountingHillClimbingConfig {
+        step_count_limit: Some(1),
+    });
+    assert!(build_acceptor::<TestSolution>(&config).is_ok());
+}
+
+#[test]
+fn great_deluge_rejects_a_ratio_that_does_not_rise() {
+    for ratio in [0.0, -0.1, f64::NAN, f64::INFINITY] {
+        let config = AcceptorConfig::GreatDeluge(GreatDelugeConfig {
+            water_level_increase_ratio: Some(ratio),
+        });
+        let error = build_acceptor::<TestSolution>(&config).expect_err("invalid ratio");
+        assert_eq!(error.field(), "water_level_increase_ratio");
+        assert!(error
+            .message()
+            .starts_with("must be finite and greater than 0"));
+    }
+    let config = AcceptorConfig::GreatDeluge(GreatDelugeConfig {
+        water_level_increase_ratio: Some(0.01),
+    });
+    assert!(build_acceptor::<TestSolution>(&config).is_ok());
+}
+
+#[test]
+fn simulated_annealing_rejects_calibration_beside_level_temperatures() {
+    let config = AcceptorConfig::SimulatedAnnealing(SimulatedAnnealingConfig {
+        level_temperatures: Some(vec![1.0]),
+        calibration: Some(SimulatedAnnealingCalibrationConfig::default()),
+        ..Default::default()
+    });
+    let error = build_acceptor::<TestSolution>(&config).expect_err("exclusive keys");
+    assert_eq!(error.field(), "calibration");
+}
diff --git a/crates/solverforge-solver/src/builder/local_search_policy.rs b/crates/solverforge-solver/src/builder/local_search_policy.rs
index ecb94a0f..4ff07693 100644
--- a/crates/solverforge-solver/src/builder/local_search_policy.rs
+++ b/crates/solverforge-solver/src/builder/local_search_policy.rs
@@ -128,7 +128,16 @@ impl CompiledForager {
 
 fn validate_acceptor(config: &AcceptorConfig, level_count: usize) -> Result<(), ConfigValueError> {
     match config {
-        AcceptorConfig::HillClimbing {} | AcceptorConfig::StepCountingHillClimbing(_) => Ok(()),
+        AcceptorConfig::HillClimbing {} => Ok(()),
+        AcceptorConfig::StepCountingHillClimbing(counting) => {
+            if counting.step_count_limit == Some(0) {
+                return Err(ConfigValueError::new(
+                    "step_count_limit",
+                    "must be greater than 0",
+                ));
+            }
+            Ok(())
+        }
         AcceptorConfig::TabuSearch(tabu) => validate_tabu_search(tabu),
         AcceptorConfig::SimulatedAnnealing(annealing) => {
             validate_simulated_annealing(annealing, level_count)
@@ -139,7 +148,13 @@ fn validate_acceptor(config: &AcceptorConfig, level_count: usize) -> Result<(),
         AcceptorConfig::DiversifiedLateAcceptance(late) => {
             positive("late_acceptance_size", late.late_acceptance_size)
         }
-        AcceptorConfig::GreatDeluge(_) => Ok(()),
+        AcceptorConfig::GreatDeluge(deluge) => match deluge.water_level_increase_ratio {
+            Some(ratio) if !(ratio.is_finite() && ratio > 0.0) => Err(ConfigValueError::new(
+                "water_level_increase_ratio",
+                format!("must be finite and greater than 0, found {ratio}"),
+            )),
+            _ => Ok(()),
+        },
     }
 }
 
@@ -180,6 +195,12 @@ fn validate_simulated_annealing(
             for &temperature in temperatures {
                 non_negative("level_temperatures", Some(temperature))?;
             }
+            if config.calibration.is_some() {
+                return Err(ConfigValueError::new(
+                    "calibration",
+                    "cannot be combined with `level_temperatures`, which set the temperatures calibration would measure",
+                ));
+            }
             Ok(())
         }
         None => validate_calibration(config.calibration.as_ref()),