diff --git a/src/Ast.zig b/src/Ast.zig
index d59e156c..22405996 100644
--- a/src/Ast.zig
+++ b/src/Ast.zig
@@ -231,11 +231,11 @@ pub fn usesFiber(self: Self, node: Node.Index, seen: *std.AutoHashMap(Node.Index
     return switch (self.nodes.items(.tag)[node]) {
         .As => try self.usesFiber(components.As.left, seen),
         .AsyncCall,
-        .Resolve,
         .Resume,
-        .Yield,
+        .Resolve,
         => true,
-        .Binary => try self.usesFiber(components.Binary.left, seen) or try self.usesFiber(components.Binary.right, seen),
+        .Binary => try self.usesFiber(components.Binary.left, seen) or
+            try self.usesFiber(components.Binary.right, seen),
         .Block => blk: {
             for (components.Block) |stmt| {
                 if (try self.usesFiber(stmt, seen)) {
@@ -264,7 +264,10 @@ pub fn usesFiber(self: Self, node: Node.Index, seen: *std.AutoHashMap(Node.Index
             break :blk false;
         },
         .Call => call: {
-            if (try self.usesFiber(components.Call.callee, seen) or (components.Call.catch_default != null and try self.usesFiber(components.Call.catch_default.?, seen))) {
+            if (try self.usesFiber(components.Call.callee, seen) or
+                (components.Call.catch_default != null and
+                try self.usesFiber(components.Call.catch_default.?, seen)))
+            {
                 break :call true;
             }
 
@@ -319,10 +322,15 @@ pub fn usesFiber(self: Self, node: Node.Index, seen: *std.AutoHashMap(Node.Index
             break :for_loop false;
         },
         .ForceUnwrap => try self.usesFiber(components.ForceUnwrap.unwrapped, seen),
-        .ForEach => try self.usesFiber(components.ForEach.iterable, seen) or try self.usesFiber(components.ForEach.key, seen) or try self.usesFiber(components.ForEach.value, seen) or try self.usesFiber(components.ForEach.body, seen),
+        .ForEach => try self.usesFiber(components.ForEach.iterable, seen) or
+            try self.usesFiber(components.ForEach.key, seen) or
+            try self.usesFiber(components.ForEach.value, seen) or
+            try self.usesFiber(components.ForEach.body, seen),
         .Function => components.Function.body != null and try self.usesFiber(components.Function.body.?, seen),
         .Grouping => try self.usesFiber(components.Grouping, seen),
-        .If => try self.usesFiber(components.If.condition, seen) or try self.usesFiber(components.If.body, seen) or (components.If.else_branch != null and try self.usesFiber(components.If.else_branch.?, seen)),
+        .If => try self.usesFiber(components.If.condition, seen) or
+            try self.usesFiber(components.If.body, seen) or (components.If.else_branch != null and
+            try self.usesFiber(components.If.else_branch.?, seen)),
         .Is => try self.usesFiber(components.Is.left, seen),
         .List => list: {
             for (components.List.items) |item| {
@@ -335,14 +343,17 @@ pub fn usesFiber(self: Self, node: Node.Index, seen: *std.AutoHashMap(Node.Index
         },
         .Map => map: {
             for (components.Map.entries) |entry| {
-                if (try self.usesFiber(entry.key, seen) or try self.usesFiber(entry.value, seen)) {
+                if (try self.usesFiber(entry.key, seen) or
+                    try self.usesFiber(entry.value, seen))
+                {
                     break :map true;
                 }
             }
 
             break :map false;
         },
-        .NamedVariable => components.NamedVariable.value != null and try self.usesFiber(components.NamedVariable.value.?, seen),
+        .NamedVariable => components.NamedVariable.value != null and
+            try self.usesFiber(components.NamedVariable.value.?, seen),
         .ObjectInit => obj_init: {
             for (components.ObjectInit.properties) |property| {
                 if (try self.usesFiber(property.value, seen)) {
@@ -353,12 +364,17 @@ pub fn usesFiber(self: Self, node: Node.Index, seen: *std.AutoHashMap(Node.Index
             break :obj_init false;
         },
         .Out => try self.usesFiber(components.Out, seen),
-        .Range => try self.usesFiber(components.Range.low, seen) or try self.usesFiber(components.Range.high, seen),
+        .Range => try self.usesFiber(components.Range.low, seen) or
+            try self.usesFiber(components.Range.high, seen),
         .Return => components.Return.value != null and try self.usesFiber(components.Return.value.?, seen),
-        .Subscript => try self.usesFiber(components.Subscript.subscripted, seen) or try self.usesFiber(components.Subscript.index, seen) or (components.Subscript.value != null and try self.usesFiber(components.Subscript.value.?, seen)),
+        .Subscript => try self.usesFiber(components.Subscript.subscripted, seen) or
+            try self.usesFiber(components.Subscript.index, seen) or
+            (components.Subscript.value != null and try self.usesFiber(components.Subscript.value.?, seen)),
         .Throw => try self.usesFiber(components.Throw.expression, seen),
         .Try => @"try": {
-            if (try self.usesFiber(components.Try.body, seen) or (components.Try.unconditional_clause != null and try self.usesFiber(components.Try.unconditional_clause.?, seen))) {
+            if (try self.usesFiber(components.Try.body, seen) or
+                (components.Try.unconditional_clause != null and try self.usesFiber(components.Try.unconditional_clause.?, seen)))
+            {
                 break :@"try" true;
             }
 
@@ -375,6 +391,7 @@ pub fn usesFiber(self: Self, node: Node.Index, seen: *std.AutoHashMap(Node.Index
         .Unwrap => try self.usesFiber(components.Unwrap.unwrapped, seen),
         .VarDeclaration => components.VarDeclaration.value != null and try self.usesFiber(components.VarDeclaration.value.?, seen),
         .While => try self.usesFiber(components.While.condition, seen) or try self.usesFiber(components.While.body, seen),
+        .Yield => false, // Yield is an issue only if the function is called within a fiber, and we already forbid async call from being jit compiled
         else => false,
     };
 }
diff --git a/src/Jit.zig b/src/Jit.zig
index aaeb9c2f..94f8dbe4 100644
--- a/src/Jit.zig
+++ b/src/Jit.zig
@@ -509,10 +509,10 @@ fn generateNode(self: *Self, node: Ast.Node.Index) Error!?m.MIR_op_t {
         .ForEach => try self.generateForEach(node),
         .TypeExpression => try self.generateTypeExpression(node),
         .TypeOfExpression => try self.generateTypeOfExpression(node),
+        .Yield => try self.generateNode(components[node].Yield),
         .AsyncCall,
         .Resume,
         .Resolve,
-        .Yield,
         => return Error.CantCompile,
 
         else => {
diff --git a/src/obj.zig b/src/obj.zig
index 34763753..2fb1250f 100644
--- a/src/obj.zig
+++ b/src/obj.zig
@@ -434,7 +434,8 @@ pub const Obj = struct {
             .List => ObjList.cast(self).?.type_def.eql(type_def),
             .Map => ObjMap.cast(self).?.type_def.eql(type_def),
             .Fiber => ObjFiber.cast(self).?.type_def.eql(type_def),
-            .UserData, .Native => unreachable, // TODO
+            .UserData => type_def.def_type == .UserData,
+            .Native => unreachable, // TODO
         };
     }