diff --git a/fastapi/params.py b/fastapi/params.py
index c44390fb9..dd4118b08 100644
--- a/fastapi/params.py
+++ b/fastapi/params.py
@@ -790,9 +790,7 @@ class Depends:
                         "\n✓ Correct: Depends(my_function)"
                         "\n✗ Wrong: Depends(my_function())"
                     )
-                elif hasattr(dependency, "__class__") and hasattr(
-                    dependency.__class__, "__call__"
-                ):
+                elif callable(dependency):
                     # Might be an instance of a callable class
                     error_msg += "\n\nIf you're using a callable class, make sure to pass the class itself or a callable instance."
 
diff --git a/test_depends_error.py b/test_depends_error.py
new file mode 100644
index 000000000..46d6e2ca8
--- /dev/null
+++ b/test_depends_error.py
@@ -0,0 +1,63 @@
+# manual_test.py
+# Run this to see the improved error messages
+
+from fastapi import FastAPI, Depends
+
+print("Testing improved error messages...\n")
+
+def get_user():
+    return {"user": "john"}
+
+# Test 1: Called function
+print("Test 1: Using Depends(get_user()) - should show helpful error")
+try:
+    app1 = FastAPI()
+    
+    @app1.get("/")
+    def route1(user = Depends(get_user())):
+        return user
+    
+    print("❌ No error raised (unexpected)")
+except TypeError as e:
+    print(f"✓ Error caught: {e}\n")
+
+# Test 2: Nested Depends
+print("Test 2: Using Depends(Depends(get_user)) - should show nested error")
+try:
+    app2 = FastAPI()
+    
+    @app2.get("/")
+    def route2(user = Depends(Depends(get_user))):
+        return user
+    
+    print("❌ No error raised (unexpected)")
+except TypeError as e:
+    print(f"✓ Error caught: {e}\n")
+
+# Test 3: String instead of callable
+print("Test 3: Using Depends('not_callable') - should show type error")
+try:
+    app3 = FastAPI()
+    
+    @app3.get("/")
+    def route3(user = Depends("not_callable")):
+        return user
+    
+    print("❌ No error raised (unexpected)")
+except TypeError as e:
+    print(f"✓ Error caught: {e}\n")
+
+# Test 4: Correct usage (should work)
+print("Test 4: Using Depends(get_user) correctly - should work")
+try:
+    app4 = FastAPI()
+    
+    @app4.get("/")
+    def route4(user = Depends(get_user)):
+        return user
+    
+    print("✓ Correct usage works! No error raised.\n")
+except Exception as e:
+    print(f"❌ Unexpected error: {e}\n")
+
+print("All manual tests completed!")
\ No newline at end of file