Object not moving to angle

I am having problems moving an object in the direction of the angle that Its moving in. I can't see whats wrong with it, but the output is definitely wrong.

Here where I declare and create an object:

Code:

struct Sprite
{
    float x, y;
    int w, h;
    int r, g, b;
    float angle, speed;
}; typedef struct Sprite Sprite;
Sprite thing;

Here I initialize some variables:

Code:

   thing.x=320; thing.y=240; 
   thing.w=10; thing.h=10;
   thing.r=255; thing.g=0; thing.b=0;
   thing.angle=90; thing.speed=2;

With an angle of 90 degrees it should move downwards, but I'm finding it moves to the left as well (as if around 110 degrees or so). Heres where I move it:

Code:

    float dx, dy;
    dx=cos(thing.angle);
    dy=sin(thing.angle);
    thing.x+=(thing.speed*dx);
    thing.y+=(thing.speed*dy);

Can anyone see whats going wrong here?

I had a look at this and tried converting the angle to radians first, which worked