GLSL: define a constant for both vertex and fragment shader

GLSL: define a constant for both vertex and fragment shader

I have a constant for defining an array in the vertex shader. I want to
use this constant also in the fragment shader to define another array of
the same size. Naive attempts fail (simply use the constant of the vertex
shader in the fragment shader or using a #define from the vertex shader).
Is this somehow possible?
The only idea I can come up with is using something like an include
statement, which seems to be added (source), but I didn't yet find the
time to implement this.
Thank you in advance!