diff --git a/src/Sema.zig b/src/Sema.zig
index e5cad45e906b3c1dc15dbae6f4119a082db5f824..e69d0829f14db68cece32fe1ab012f6324af0d8f 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -17763,7 +17763,7 @@ fn resolvePeerTypes(
                     }
 
                     // Merge errors
-                    err_set_ty = try err_set_ty.?.errorSetMerge(sema.arena, candidate_ty);
+                    err_set_ty = try candidate_ty.errorSetMerge(sema.arena, err_set_ty.?);
                     chosen = candidate;
                     chosen_i = candidate_i + 1;
                     continue;
@@ -17850,7 +17850,7 @@ fn resolvePeerTypes(
                     }
 
                     // Not a superset, create merged error set
-                    err_set_ty = try err_set_ty.?.errorSetMerge(sema.arena, eu_set_ty);
+                    err_set_ty = try eu_set_ty.errorSetMerge(sema.arena, err_set_ty.?);
                     chosen = candidate;
                     chosen_i = candidate_i + 1;
                     continue;
diff --git a/test/behavior/cast.zig b/test/behavior/cast.zig
index af2eef03f1cc6daf68c296d41803078dfb209be5..9ecfaa5edbc038f447e95a38e33fa7493a78fab5 100644
--- a/test/behavior/cast.zig
+++ b/test/behavior/cast.zig
@@ -669,27 +669,27 @@ test "peer type resolution: disjoint error sets" {
     const a: error{ One, Two } = undefined;
     const b: error{Three} = undefined;
 
-    // note: order of error set members doesn't member, may want to sort
+    // note: order of error set made to match stage1 during stage2 dev
 
     {
         const ty = @TypeOf(a, b);
         const error_set_info = @typeInfo(ty);
         try expect(error_set_info == .ErrorSet);
         try expect(error_set_info.ErrorSet.?.len == 3);
-        try expect(mem.eql(u8, error_set_info.ErrorSet.?[0].name, "One"));
-        try expect(mem.eql(u8, error_set_info.ErrorSet.?[1].name, "Two"));
-        try expect(mem.eql(u8, error_set_info.ErrorSet.?[2].name, "Three"));
-    }
-
-    {
-        const ty = @TypeOf(b, a);
-        const error_set_info = @typeInfo(ty);
-        try expect(error_set_info == .ErrorSet);
-        try expect(error_set_info.ErrorSet.?.len == 3);
         try expect(mem.eql(u8, error_set_info.ErrorSet.?[0].name, "Three"));
         try expect(mem.eql(u8, error_set_info.ErrorSet.?[1].name, "One"));
         try expect(mem.eql(u8, error_set_info.ErrorSet.?[2].name, "Two"));
     }
+
+    {
+        const ty = @TypeOf(b, a);
+        const error_set_info = @typeInfo(ty);
+        try expect(error_set_info == .ErrorSet);
+        try expect(error_set_info.ErrorSet.?.len == 3);
+        try expect(mem.eql(u8, error_set_info.ErrorSet.?[0].name, "One"));
+        try expect(mem.eql(u8, error_set_info.ErrorSet.?[1].name, "Two"));
+        try expect(mem.eql(u8, error_set_info.ErrorSet.?[2].name, "Three"));
+    }
 }
 
 test "peer type resolution: error union and error set" {
@@ -701,7 +701,7 @@ test "peer type resolution: error union and error set" {
     const a: error{Three} = undefined;
     const b: error{ One, Two }!u32 = undefined;
 
-    // note: order of error set members doesn't member, may want to sort
+    // note: order of error set made to match stage1 during stage2 dev
 
     {
         const ty = @TypeOf(a, b);
@@ -710,9 +710,9 @@ test "peer type resolution: error union and error set" {
 
         const error_set_info = @typeInfo(info.ErrorUnion.error_set);
         try expect(error_set_info.ErrorSet.?.len == 3);
-        try expect(mem.eql(u8, error_set_info.ErrorSet.?[0].name, "Three"));
-        try expect(mem.eql(u8, error_set_info.ErrorSet.?[1].name, "One"));
-        try expect(mem.eql(u8, error_set_info.ErrorSet.?[2].name, "Two"));
+        try expect(mem.eql(u8, error_set_info.ErrorSet.?[0].name, "One"));
+        try expect(mem.eql(u8, error_set_info.ErrorSet.?[1].name, "Two"));
+        try expect(mem.eql(u8, error_set_info.ErrorSet.?[2].name, "Three"));
     }
 
     {
@@ -737,7 +737,7 @@ test "peer type resolution: error union after non-error" {
     const a: u32 = undefined;
     const b: error{ One, Two }!u32 = undefined;
 
-    // note: order of error set members doesn't member, may want to sort
+    // note: order of error set made to match stage1 during stage2 dev
 
     {
         const ty = @TypeOf(a, b);