diff --git a/src/main.rs b/src/main.rs
index 1f2c6a1..527fbae 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -19,11 +19,35 @@ fn main() {
         .as_ref()
         .map_or("", |package_name| package_name.as_str());
 
+    // If kernel_major is set, the app requires kernel ^kernel_major.0 (>=
+    // kernel_major.0, < (kernel_major+1).0) Optionally, kernel_minor can be
+    // set, making the app require ^kernel_major.kernel_minor (>=
+    // kernel_major.kernel_minor, < (kernel_major+1).0).
+    let minimum_tock_kernel_version = match opt.kernel_major {
+        Some(major) => Some((major, opt.kernel_minor.unwrap_or(0))),
+        None => None,
+    };
+
     // Create the metadata.toml file needed for the TAB file.
     let mut metadata_toml = String::new();
+    // TAB version is currently "1". This defines the general format, but
+    // key-value pairs can be added (or removed) and still be version 1.
     writeln!(&mut metadata_toml, "tab-version = 1").unwrap();
+    // Name is always set by elf2tab (even if it is empty).
     writeln!(&mut metadata_toml, "name = \"{}\"", package_name).unwrap();
+    // We don't currently tell elf2tab if this app only runs on certain boards.
     writeln!(&mut metadata_toml, "only-for-boards = \"\"").unwrap();
+    // Include "minimum-tock-kernel-version" key if a necessary kernel version
+    // was specified.
+    minimum_tock_kernel_version.map(|(major, minor)| {
+        writeln!(
+            &mut metadata_toml,
+            "minimum-tock-kernel-version = \"{}.{}\"",
+            major, minor
+        )
+        .unwrap();
+    });
+    // Add build-date metadata unless a deterministic build is desired.
     if !opt.deterministic {
         let build_date = chrono::Utc::now().to_rfc3339_opts(chrono::SecondsFormat::Secs, true);
         writeln!(&mut metadata_toml, "build-date = {}", build_date).unwrap();
@@ -81,13 +105,7 @@ fn main() {
             opt.kernel_heap_size,
             opt.protected_region_size,
             opt.permissions.to_vec(),
-            // If kernel_major is set, the app requires kernel ^kernel_major.0 (>= kernel_major.0, < (kernel_major+1).0)
-            // Optionally, kernel_minor can be set, making the app require ^kernel_major.kernel_minor
-            // (>= kernel_major.kernel_minor, < (kernel_major+1).0)
-            match opt.kernel_major {
-                Some(major) => Some((major, opt.kernel_minor.unwrap_or(0))),
-                None => None,
-            },
+            minimum_tock_kernel_version,
         )
         .unwrap();
         if opt.verbose {