diff --git a/Cargo.lock b/Cargo.lock
index c49cccb..3049b1f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1753,6 +1753,22 @@ version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "df3b46402a9d5adb4c86a0cf463f42e19994e3ee891101b1841f30a545cb49a9"
 
+[[package]]
+name = "humantime"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a3a5bfb195931eeb336b2a7b4d761daec841b97f947d34394601737a7bba5e4"
+
+[[package]]
+name = "humantime-serde"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57a3db5ea5923d99402c94e9feb261dc5ee9b4efa158b0315f788cf549cc200c"
+dependencies = [
+ "humantime",
+ "serde",
+]
+
 [[package]]
 name = "hyper"
 version = "0.14.27"
@@ -3386,6 +3402,8 @@ dependencies = [
  "futures",
  "glob",
  "hex",
+ "humantime",
+ "humantime-serde",
  "hyper",
  "itertools 0.11.0",
  "num",
diff --git a/Cargo.toml b/Cargo.toml
index 351b321..30e039a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,6 +21,8 @@ clap = { version = "4", features = ["derive", "env"] }
 ethereum-types = "0.14"
 futures = "0.3"
 hex = "0.4"
+humantime = "2.1.0"
+humantime-serde = "1.1.1"
 hyper = "0.14"
 itertools = "0.11"
 num = "0.4"
diff --git a/src/infra/config/dex/file.rs b/src/infra/config/dex/file.rs
index 2449543..aafcbec 100644
--- a/src/infra/config/dex/file.rs
+++ b/src/infra/config/dex/file.rs
@@ -54,12 +54,12 @@ struct Config {
     back_off_growth_factor: f64,
 
     /// Minimum back-off time in seconds for rate limiting.
-    #[serde(default = "default_min_back_off")]
-    min_back_off: u64,
+    #[serde(with = "humantime_serde", default = "default_min_back_off")]
+    min_back_off: Duration,
 
     /// Maximum back-off time in seconds for rate limiting.
-    #[serde(default = "default_max_back_off")]
-    max_back_off: u64,
+    #[serde(with = "humantime_serde", default = "default_max_back_off")]
+    max_back_off: Duration,
 
     /// Settings specific to the wrapped dex API.
     dex: toml::Value,
@@ -81,12 +81,12 @@ fn default_back_off_growth_factor() -> f64 {
     2.0
 }
 
-fn default_min_back_off() -> u64 {
-    1
+fn default_min_back_off() -> Duration {
+    Duration::from_secs(1)
 }
 
-fn default_max_back_off() -> u64 {
-    8
+fn default_max_back_off() -> Duration {
+    Duration::from_secs(8)
 }
 
 /// Loads the base solver configuration from a TOML file.
@@ -144,8 +144,8 @@ pub async fn load<T: DeserializeOwned>(path: &Path) -> (super::Config, T) {
         },
         rate_limiting_strategy: RateLimitingStrategy::try_new(
             config.back_off_growth_factor,
-            Duration::from_secs(config.min_back_off),
-            Duration::from_secs(config.max_back_off),
+            config.min_back_off,
+            config.max_back_off,
         )
         .unwrap(),
     };