diff --git a/litex/soc/integration/cpu_interface.py b/litex/soc/integration/cpu_interface.py
index 99b569776..d8020a892 100644
--- a/litex/soc/integration/cpu_interface.py
+++ b/litex/soc/integration/cpu_interface.py
@@ -72,7 +72,7 @@ def get_linker_regions(regions):
 
 def get_mem_header(regions, flash_boot_address):
     r = generated_banner("//")
-    r = "#ifndef __GENERATED_MEM_H\n#define __GENERATED_MEM_H\n\n"
+    r += "#ifndef __GENERATED_MEM_H\n#define __GENERATED_MEM_H\n\n"
     for name, base, size in regions:
         r += "#define {name}_BASE 0x{base:08x}\n#define {name}_SIZE 0x{size:08x}\n\n".format(name=name.upper(), base=base, size=size)
     if flash_boot_address is not None: