diff --git a/test/behavior/cast.zig b/test/behavior/cast.zig
index 0e74cd0b58..8c9f2b285d 100644
--- a/test/behavior/cast.zig
+++ b/test/behavior/cast.zig
@@ -251,6 +251,9 @@ test "*const ?[*]const T to [*c]const [*c]const T" {
 test "array coersion to undefined at runtime" {
     @setRuntimeSafety(true);
 
+    // setRuntimeSafety isn't recognized on stage2
+    if (@import("builtin").zig_is_stage2 and (@import("builtin").mode != .Debug or @import("builtin").mode != .ReleaseSafe)) return error.SkipZigTest;
+
     var array = [4]u8{ 3, 4, 5, 6 };
     var undefined_val = [4]u8{ 0xAA, 0xAA, 0xAA, 0xAA };
 
diff --git a/test/behavior/int128.zig b/test/behavior/int128.zig
index 18375a3e17..5113ca63eb 100644
--- a/test/behavior/int128.zig
+++ b/test/behavior/int128.zig
@@ -20,6 +20,9 @@ test "uint128" {
 test "undefined 128 bit int" {
     @setRuntimeSafety(true);
 
+    // setRuntimeSafety isn't recognized on stage2
+    if (@import("builtin").zig_is_stage2 and (@import("builtin").mode != .Debug or @import("builtin").mode != .ReleaseSafe)) return error.SkipZigTest;
+
     var undef: u128 = undefined;
     var undef_signed: i128 = undefined;
     try expect(undef == 0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa and @bitCast(u128, undef_signed) == undef);