diff --git a/stage0/stages_test.zig b/stage0/stages_test.zig
index 07c997cae4..aafa7c33f7 100644
--- a/stage0/stages_test.zig
+++ b/stage0/stages_test.zig
@@ -71,12 +71,29 @@ fn stagesCheck(gpa: Allocator, source: [:0]const u8, src_path: []const u8, check
         var result = try sema_c.cSema(gpa, @bitCast(c_zir));
         defer result.deinit(gpa);
 
-        // Run Zig sema on the same source and verify it succeeds.
         var zig_result = try sema.zigSema(gpa, src_path);
         defer zig_result.deinit();
+
+        // Compare per-function Air: C and Zig must produce the same count.
+        const zig_air_text = zig_result.air_output.written();
+        const zig_func_count = countAirSections(zig_air_text);
+        try std.testing.expectEqual(zig_func_count, result.func_airs.len);
     }
 }
 
+/// Count the number of per-function Air sections in verbose_air output.
+/// Sections are delimited by "# Begin Function AIR: " markers.
+fn countAirSections(text: []const u8) usize {
+    const marker = "# Begin Function AIR: ";
+    var count: usize = 0;
+    var pos: usize = 0;
+    while (std.mem.indexOfPos(u8, text, pos, marker)) |begin| {
+        count += 1;
+        pos = begin + marker.len;
+    }
+    return count;
+}
+
 const last_successful_corpus = "../lib/std/crypto/codecs.zig";
 
 // find ../{lib,src} -name '*.zig' | xargs -n1 stat -c "%s %n" | sort -n | awk '{printf "    \""$2"\", // "$1"\n"}'