diff --git a/include/lib/mmio.h b/include/lib/mmio.h
index d3c2cae..5d33c59 100644
--- a/include/lib/mmio.h
+++ b/include/lib/mmio.h
@@ -33,13 +33,13 @@
 
 #include <stdint.h>
 
-extern void mmio_write_8(uintptr_t addr, uint8_t value);
-extern uint8_t mmio_read_8(uintptr_t addr);
+void mmio_write_8(uintptr_t addr, uint8_t value);
+uint8_t mmio_read_8(uintptr_t addr);
 
-extern void mmio_write_32(uintptr_t addr, uint32_t value);
-extern uint32_t mmio_read_32(uintptr_t addr);
+void mmio_write_32(uintptr_t addr, uint32_t value);
+uint32_t mmio_read_32(uintptr_t addr);
 
-extern void mmio_write_64(uintptr_t addr, uint64_t value);
-extern uint64_t mmio_read_64(uintptr_t addr);
+void mmio_write_64(uintptr_t addr, uint64_t value);
+uint64_t mmio_read_64(uintptr_t addr);
 
 #endif /* __MMIO_H__ */