diff --git a/src/class.zig b/src/class.zig
index 738b42f..d5f4ff2 100644
--- a/src/class.zig
+++ b/src/class.zig
@@ -63,14 +63,14 @@ pub const Class = struct {
     /// allows adding new methods; returns true on success.
     // imp should be a function with C calling convention
     // whose first two arguments are a `c.id` and a `c.SEL`.
-    pub fn addMethod(self: Class, name: [:0]const u8, imp: anytype) bool {
+    pub fn addMethod(self: Class, name: [:0]const u8, imp: anytype) !bool {
         const fn_info = @typeInfo(@TypeOf(imp)).Fn;
         assert(fn_info.calling_convention == .C);
         assert(fn_info.is_var_args == false);
         assert(fn_info.params.len >= 2);
         assert(fn_info.params[0].type == c.id);
         assert(fn_info.params[1].type == c.SEL);
-        const str = objc.encodeFn(fn_info.return_type.?, fn_info.params) catch @panic("OOM!");
+        const str = try objc.createFnSignature(fn_info.return_type.?, fn_info.params);
         defer std.heap.raw_c_allocator.free(str);
         return c.class_addMethod(self.value, objc.sel(name).value, @ptrCast(&imp), str.ptr);
     }
@@ -195,3 +195,23 @@ test "Ivars" {
     const slice = std.mem.sliceTo(my_ivar.getProperty([*c]const u8, "UTF8String"), 0);
     try testing.expectEqualSlices(u8, "69---nice", slice);
 }
+
+test "addMethod" {
+    const testing = std.testing;
+    const My_Class = setup: {
+        const My_Class = allocateClassPair(objc.getClass("NSObject").?, "my_class").?;
+        defer registerClassPair(My_Class);
+        std.debug.assert(try My_Class.addMethod("my_addition", struct {
+            fn imp(target: objc.c.id, sel: objc.c.SEL, a: i32, b: i32) callconv(.C) i32 {
+                _ = sel;
+                _ = target;
+                return a + b;
+            }
+        }.imp));
+        break :setup My_Class;
+    };
+    const result = My_Class.msgSend(objc.Object, "alloc", .{})
+        .msgSend(objc.Object, "init", .{})
+        .msgSend(i32, "my_addition", .{ @as(i32, 2), @as(i32, 3) });
+    try testing.expectEqual(@as(i32, 5), result);
+}