diff --git a/include/libopencm3/cm3/common.h b/include/libopencm3/cm3/common.h
index a6cfb22e..bbd04cba 100644
--- a/include/libopencm3/cm3/common.h
+++ b/include/libopencm3/cm3/common.h
@@ -17,8 +17,8 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef CM3_COMMON_H
-#define CM3_COMMON_H
+#ifndef LIBOPENCM3_CM3_COMMON_H
+#define LIBOPENCM3_CM3_COMMON_H
 
 #include <stdint.h>
 #include <stdbool.h>
diff --git a/include/libopencm3/cm3/memorymap.h b/include/libopencm3/cm3/memorymap.h
index 6f8b49d6..b1b51729 100644
--- a/include/libopencm3/cm3/memorymap.h
+++ b/include/libopencm3/cm3/memorymap.h
@@ -17,8 +17,8 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef CM3_MEMORYMAP_H
-#define CM3_MEMORYMAP_H
+#ifndef LIBOPENCM3_CM3_MEMORYMAP_H
+#define LIBOPENCM3_CM3_MEMORYMAP_H
 
 /* --- ARM Cortex-M3 specific definitions ---------------------------------- */