diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 7e3861e2f..7e8a1b9d1 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -125,14 +125,17 @@ MixFlakeOptions::MixFlakeOptions()
 
     addFlag({
         .longName = "override-input",
-        .description = "Override a specific flake input (e.g. `dwarffs/nixpkgs`). This implies `--no-write-lock-file`.",
+        .description =
+            "Override a specific flake input (e.g. `dwarffs/nixpkgs`). The input path must not be empty. This implies `--no-write-lock-file`.",
         .category = category,
         .labels = {"input-path", "flake-url"},
         .handler = {[&](std::string inputAttrPath, std::string flakeRef) {
             lockFlags.writeLockFile = false;
+            auto path = flake::parseInputAttrPath(inputAttrPath);
+            if (path.empty())
+                throw UsageError("--override-input: input path cannot be empty");
             lockFlags.inputOverrides.insert_or_assign(
-                flake::parseInputAttrPath(inputAttrPath),
-                parseFlakeRef(fetchSettings, flakeRef, absPath(getCommandBaseDir()).string(), true));
+                std::move(path), parseFlakeRef(fetchSettings, flakeRef, absPath(getCommandBaseDir()).string(), true));
         }},
         .completer = {[&](AddCompletions & completions, size_t n, std::string_view prefix) {
             if (n == 0) {
diff --git a/tests/functional/flakes/flakes.sh b/tests/functional/flakes/flakes.sh
index d9e187251..c7f0771f9 100755
--- a/tests/functional/flakes/flakes.sh
+++ b/tests/functional/flakes/flakes.sh
@@ -395,6 +395,9 @@ nix flake lock "$flake3Dir" --override-input flake2/flake1 flake1
 nix flake lock "$flake3Dir" --override-input flake2/flake1 flake1/master/"$hash1"
 [[ $(jq -r .nodes.flake1_2.locked.rev "$flake3Dir/flake.lock") =~ $hash1 ]]
 
+# Test that --override-input with empty input path is rejected (issue #14816).
+expectStderr 1 nix flake lock "$flake3Dir" --override-input '' . | grepQuiet "input path cannot be empty"
+
 # Test --update-input.
 nix flake lock "$flake3Dir"
 [[ $(jq -r .nodes.flake1_2.locked.rev "$flake3Dir/flake.lock") = "$hash1" ]]