diff --git a/src/Allocator.sol b/src/Allocator.sol
index efd4134..62efe54 100644
--- a/src/Allocator.sol
+++ b/src/Allocator.sol
@@ -110,10 +110,11 @@ contract Allocator is Initializable, Ownable2StepUpgradeable, UUPSUpgradeable, I
         uint256 allowanceBefore = allowance(allocator);
         if (allowanceBefore == 0) {
             revert AlreadyZero();
-        } else if (allowanceBefore < amount) {
-            amount = allowanceBefore;
+        } else if (allowanceBefore <= amount) {
+            _allocators.remove(allocator);
+        } else {
+            _allocators.set(allocator, allowanceBefore - amount);
         }
-        _allocators.set(allocator, allowanceBefore - amount);
         emit AllowanceChanged(allocator, allowanceBefore, allowance(allocator));
     }
 
diff --git a/test/Allocator.t.sol b/test/Allocator.t.sol
index a56cc87..61ba0f9 100644
--- a/test/Allocator.t.sol
+++ b/test/Allocator.t.sol
@@ -301,4 +301,20 @@ contract AllocatorTest is Test {
         emit IAllocator.AllowanceChanged(vm.addr(1), 100, 50);
         allocator.decreaseAllowance(vm.addr(1), 50);
     }
+
+    function testDecreaseAllowanceRemoveAllocator() public {
+        allocator.setAllowance(vm.addr(1), 100);
+        allocator.setAllowance(vm.addr(2), 100);
+        address[] memory allocators = allocator.getAllocators();
+        assertEq(allocators[0], vm.addr(1));
+        assertEq(allocators[1], vm.addr(2));
+        assertEq(allocators.length, 2);
+        allocator.decreaseAllowance(vm.addr(1), 150);
+        allocators = allocator.getAllocators();
+        assertEq(allocators[0], vm.addr(2));
+        assertEq(allocators.length, 1);
+        allocator.decreaseAllowance(vm.addr(2), 100);
+        allocators = allocator.getAllocators();
+        assertEq(allocators.length, 0);
+    }
 }