diff --git a/cpu/mips_pic32mx/include/periph_cpu.h b/cpu/mips_pic32mx/include/periph_cpu.h
index 9fca77223..07c3db92f 100644
--- a/cpu/mips_pic32mx/include/periph_cpu.h
+++ b/cpu/mips_pic32mx/include/periph_cpu.h
@@ -8,6 +8,9 @@
  *
  */
 
+#ifndef PERIPH_CPU_H
+#define PERIPH_CPU_H
+
 #include "periph_cpu_common.h"
 
 #ifdef __cplusplus
@@ -17,3 +20,5 @@ extern "C" {
 #ifdef __cplusplus
 }
 #endif
+
+#endif /* PERIPH_CPU_H */
diff --git a/cpu/mips_pic32mz/include/periph_cpu.h b/cpu/mips_pic32mz/include/periph_cpu.h
index 9fca77223..07c3db92f 100644
--- a/cpu/mips_pic32mz/include/periph_cpu.h
+++ b/cpu/mips_pic32mz/include/periph_cpu.h
@@ -8,6 +8,9 @@
  *
  */
 
+#ifndef PERIPH_CPU_H
+#define PERIPH_CPU_H
+
 #include "periph_cpu_common.h"
 
 #ifdef __cplusplus
@@ -17,3 +20,5 @@ extern "C" {
 #ifdef __cplusplus
 }
 #endif
+
+#endif /* PERIPH_CPU_H */
diff --git a/sys/quad_math/quad.h b/sys/quad_math/quad.h
index 38e89b9a7..46d02379e 100644
--- a/sys/quad_math/quad.h
+++ b/sys/quad_math/quad.h
@@ -49,6 +49,9 @@
  * with 48-bit ints.
  */
 
+#ifndef QUAD_H
+#define QUAD_H
+
 #include <sys/types.h>
 #include <limits.h>
 
@@ -147,3 +150,5 @@ quad_t __xordi3(quad_t, quad_t);
 #ifdef __cplusplus
 }
 #endif
+
+#endif /* QUAD_H */