diff --git a/keyboards/planck/rev7/matrix.c b/keyboards/planck/rev7/matrix.c
index df1e627e83..c89c399a40 100644
--- a/keyboards/planck/rev7/matrix.c
+++ b/keyboards/planck/rev7/matrix.c
@@ -19,6 +19,7 @@
 #include "hal_pal.h"
 #include "hal_pal_lld.h"
 #include "quantum.h"
+#include <math.h>
 
 // STM32-specific watchdog config calculations
 // timeout = 31.25us * PR * (RL + 1)