diff --git a/src/benchmark/benchmark_result.rs b/src/benchmark/benchmark_result.rs
index 69de16c..27d41a4 100644
--- a/src/benchmark/benchmark_result.rs
+++ b/src/benchmark/benchmark_result.rs
@@ -2,6 +2,15 @@ use std::collections::BTreeMap;
 
 use serde::Serialize;
 
+/// Parameter value and whether it was used in the command line template
+#[derive(Debug, Default, Clone, Serialize, PartialEq)]
+#[serde(transparent)]
+pub struct Parameter {
+    pub value: String,
+    #[serde(skip)]
+    pub is_unused: bool,
+}
+
 /// Set of values that will be exported.
 // NOTE: `serde` is used for JSON serialization, but not for CSV serialization due to the
 // `parameters` map. Update `src/hyperfine/export/csv.rs` with new fields, as appropriate.
@@ -49,5 +58,5 @@ pub struct BenchmarkResult {
 
     /// Parameter values for this benchmark
     #[serde(skip_serializing_if = "BTreeMap::is_empty")]
-    pub parameters: BTreeMap<String, String>,
+    pub parameters: BTreeMap<String, Parameter>,
 }
diff --git a/src/benchmark/mod.rs b/src/benchmark/mod.rs
index a45f9a0..ecf1302 100644
--- a/src/benchmark/mod.rs
+++ b/src/benchmark/mod.rs
@@ -19,7 +19,7 @@ use crate::output::warnings::{OutlierWarningOptions, Warnings};
 use crate::parameter::ParameterNameAndValue;
 use crate::quantity::{byte, const_time_from_seconds, ratio, second, FormatQuantity, Time, Zero};
 use crate::util::exit_code::extract_exit_code;
-use benchmark_result::BenchmarkResult;
+use benchmark_result::{BenchmarkResult, Parameter};
 use measurement::{Measurement, Measurements};
 
 use anyhow::{anyhow, Result};
@@ -474,7 +474,15 @@ impl<'a> Benchmark<'a> {
                 .command
                 .get_parameters()
                 .iter()
-                .map(|(name, value)| (name.to_string(), value.to_string()))
+                .map(|(name, value)| {
+                    (
+                        name.to_string(),
+                        Parameter {
+                            value: value.to_string(),
+                            is_unused: self.command.is_parameter_unused(name),
+                        },
+                    )
+                })
                 .collect(),
         })
     }
diff --git a/src/export/csv.rs b/src/export/csv.rs
index f471178..331b52e 100644
--- a/src/export/csv.rs
+++ b/src/export/csv.rs
@@ -53,7 +53,7 @@ impl Exporter for CsvExporter {
                 fields.push(Cow::Owned(format!("{f:.CSV_PRECISION$}").into_bytes()))
             }
             for v in res.parameters.values() {
-                fields.push(Cow::Borrowed(v.as_bytes()))
+                fields.push(Cow::Borrowed(v.value.as_bytes()))
             }
             writer.write_record(fields)?;
         }
@@ -64,6 +64,7 @@ impl Exporter for CsvExporter {
 
 #[test]
 fn test_csv() {
+    use crate::benchmark::benchmark_result::Parameter;
     use std::collections::BTreeMap;
     let exporter = CsvExporter::default();
 
@@ -83,8 +84,20 @@ fn test_csv() {
             exit_codes: vec![Some(0), Some(0), Some(0)],
             parameters: {
                 let mut params = BTreeMap::new();
-                params.insert("foo".into(), "one".into());
-                params.insert("bar".into(), "two".into());
+                params.insert(
+                    "foo".into(),
+                    Parameter {
+                        value: "one".into(),
+                        is_unused: false,
+                    },
+                );
+                params.insert(
+                    "bar".into(),
+                    Parameter {
+                        value: "two".into(),
+                        is_unused: false,
+                    },
+                );
                 params
             },
         },
@@ -103,8 +116,20 @@ fn test_csv() {
             exit_codes: vec![Some(0), Some(0), Some(0)],
             parameters: {
                 let mut params = BTreeMap::new();
-                params.insert("foo".into(), "one".into());
-                params.insert("bar".into(), "seven".into());
+                params.insert(
+                    "foo".into(),
+                    Parameter {
+                        value: "one".into(),
+                        is_unused: false,
+                    },
+                );
+                params.insert(
+                    "bar".into(),
+                    Parameter {
+                        value: "seven".into(),
+                        is_unused: false,
+                    },
+                );
                 params
             },
         },