diff --git a/include/validator.h b/include/validator.h
new file mode 100644
index 0000000..030fbdf
--- /dev/null
+++ b/include/validator.h
@@ -0,0 +1,26 @@
+#ifndef _BOOTSTRAP_VALIDATOR_H
+#define _BOOTSTRAP_VALIDATOR_H
+
+#include "cJSON.h"
+#include "dyn_array.h"
+
+enum PromptType {
+  PT_STRING = 1,
+};
+
+struct Prompt {
+  const char *key;
+  enum PromptType type;
+};
+
+enum SpecValidationError {
+  SVE_NOT_TOPLEVEL_OBJECT = 1,
+  // The value of a top-level key does not correspond to one of the following:
+  // * "$STRING"
+  SVE_INVALID_VALUE,
+};
+
+enum SpecValidationError
+validate_spec_json(const cJSON *const parsed, struct DynArray **prompts);
+
+#endif /* _BOOTSTRAP_VALIDATOR_H */
diff --git a/main.c b/main.c
index e48c21c..12c5489 100644
--- a/main.c
+++ b/main.c
@@ -5,6 +5,7 @@
 #include "cJSON.h"
 #include "config.h"
 #include "parser.h"
+#include "validator.h"
 
 const char *ENV_BOOTSTRAP_ROOT_DIR = "BOOTSTRAP_ROOT_DIR";
 
@@ -51,10 +52,27 @@ int main(int argc, char **argv) {
     goto config_cleanup;
   }
 
+  // `parsed` must be free'd.
+
+  struct DynArray *prompts = 0;
+  switch (validate_spec_json(parsed, &prompts)) {
+  case SVE_NOT_TOPLEVEL_OBJECT:
+    fprintf(stderr, "`spec.json` top-level JSON value must be object.");
+    retval = EXIT_FAILURE;
+    goto parsed_cleanup;
+  case SVE_INVALID_VALUE:
+    fprintf(stderr, "Encountered unknown `spec.json` value type.");
+    retval = EXIT_FAILURE;
+    goto parsed_cleanup;
+  }
+
   // TODO: Extract the prompts out of the `spec.json` file.
   // TODO: Load in the curses interface.
   // TODO: Run `run.sh`.
 
+parsed_cleanup:
+  cJSON_Delete(parsed);
+
 config_cleanup:
   config_free(config);
 
diff --git a/specs/clang/spec.json b/specs/clang/spec.json
new file mode 100644
index 0000000..fe51488
--- /dev/null
+++ b/specs/clang/spec.json
@@ -0,0 +1 @@
+[]
diff --git a/src/validator.c b/src/validator.c
new file mode 100644
index 0000000..8c94e65
--- /dev/null
+++ b/src/validator.c
@@ -0,0 +1,28 @@
+#include <assert.h>
+
+#include "validator.h"
+
+enum SpecValidationError
+validate_spec_json(const cJSON *const parsed, struct DynArray **prompts) {
+  *prompts = 0;
+
+  if (!parsed) {
+    // Indicates no `spec.json` file was found.
+    return 0;
+  }
+
+  if (!cJSON_IsObject(parsed)) {
+    return SVE_NOT_TOPLEVEL_OBJECT;
+  }
+
+  enum SpecValidationError retval = 0;
+  // `cJSON_GetArraySize` works because internally objects are stored as arrays.
+  *prompts = dyn_array_new(cJSON_GetArraySize(parsed));
+
+  assert(0);
+
+cleanup:
+  dyn_array_free(*prompts);
+  *prompts = 0;
+  return retval;
+}
diff --git a/test/runner.c b/test/runner.c
index 15bb7b7..556f3d5 100644
--- a/test/runner.c
+++ b/test/runner.c
@@ -3,6 +3,7 @@
 #include "test_dyn_array.h"
 #include "test_parser.h"
 #include "test_path.h"
+#include "test_validator.h"
 
 int main(int argc, char *argv[]) {
   sput_start_testing();
@@ -25,6 +26,9 @@ int main(int argc, char *argv[]) {
   sput_run_test(test_parse_spec_json_minimal);
   sput_run_test(test_parse_spec_json_invalid);
 
+  sput_enter_suite("validator");
+  sput_run_test(test_validate_spec_json_not_toplevel_object);
+
   sput_finish_testing();
 
   return sput_get_return_value();
diff --git a/test/test_parser.h b/test/test_parser.h
index 5771f4f..f72d4b8 100644
--- a/test/test_parser.h
+++ b/test/test_parser.h
@@ -1,5 +1,5 @@
-#ifndef _BOOTSTRAP_TEST_LOADER
-#define _BOOTSTRAP_TEST_LOADER
+#ifndef _BOOTSTRAP_TEST_PARSER
+#define _BOOTSTRAP_TEST_PARSER
 
 #include <unistd.h>
 
@@ -81,4 +81,4 @@ static void test_parse_spec_json_invalid() {
   free(root_dir);
 }
 
-#endif /* _BOOTSTRAP_TEST_LOADER */
+#endif /* _BOOTSTRAP_TEST_PARSER */
diff --git a/test/test_validator.h b/test/test_validator.h
new file mode 100644
index 0000000..f6fe05f
--- /dev/null
+++ b/test/test_validator.h
@@ -0,0 +1,17 @@
+#ifndef _BOOTSTRAP_TEST_VALIDATOR
+#define _BOOTSTRAP_TEST_VALIDATOR
+
+#include "dyn_array.h"
+#include "sput.h"
+#include "validator.h"
+
+static void test_validate_spec_json_not_toplevel_object() {
+  struct DynArray *prompts = 0;
+  cJSON *parsed = cJSON_Parse("[]");
+  enum SpecValidationError retval = validate_spec_json(parsed, &prompts);
+  sput_fail_unless(retval == SVE_NOT_TOPLEVEL_OBJECT, "not top-level object");
+
+  cJSON_Delete(parsed);
+}
+
+#endif /* _BOOTSTRAP_TEST_VALIDATOR */