diff --git a/tools/versioner/src/versioner.cpp b/tools/versioner/src/versioner.cpp
index af0c067..73eff0e 100644
--- a/tools/versioner/src/versioner.cpp
+++ b/tools/versioner/src/versioner.cpp
@@ -33,7 +33,6 @@
 #include <iostream>
 #include <map>
 #include <memory>
-#include <optional>
 #include <set>
 #include <sstream>
 #include <string>
@@ -519,8 +518,11 @@
       }
 
       case 'r': {
-        Arch arch = arch_from_string(optarg);
-        selected_architectures.insert(arch);
+        std::optional<Arch> arch = arch_from_string(optarg);
+        if (!arch) {
+          errx(1, "unknown architecture '%s'", optarg);
+        }
+        selected_architectures.insert(*arch);
         break;
       }
 
@@ -613,6 +615,9 @@
     std::string versioner_dir = to_string(top) + "/bionic/tools/versioner";
     location.header_path = versioner_dir + "/current";
     location.dependency_dir = versioner_dir + "/dependencies";
+    if (platform_dir.empty()) {
+      platform_dir = versioner_dir + "/platforms";
+    }
   } else {
     if (!android::base::Realpath(argv[optind], &location.header_path)) {
       err(1, "failed to get realpath for path '%s'", argv[optind]);
@@ -653,6 +658,12 @@
 
   compilation_types = generateCompilationTypes(selected_architectures, selected_levels);
 
+  // Do this before compiling so that we can early exit if the platforms don't match what we
+  // expect.
+  if (!platform_dir.empty()) {
+    symbol_database = parsePlatforms(compilation_types, platform_dir);
+  }
+
   auto start = std::chrono::high_resolution_clock::now();
   std::unique_ptr<HeaderDatabase> declaration_database =
       compileHeaders(compilation_types, location);