read input variable in makefile and set variable upon its name

I have a makefile where I want to read module name from input and then make directory based on its name. here is my code:

build:  
    @read -p "Enter Module Name:" module;  
    module_dir=./modules/$$module  
    mkdir -p $$module_dir/build;  

But after setting module_dir, it contains only ./modules/ (with no module name concatenated).

What is wrong in my code?

Each command runs in its own subshell, so variables can't survive from one command to the next. Put them on the same line and they'll work:

build:  
    @read -p "Enter Module Name:" module; \  
    module_dir=./modules/$$module; \
    mkdir -p $$module_dir/build