diff --git a/os/various/chprintf.c b/os/various/chprintf.c
index 50124d438..e44bd9d5b 100644
--- a/os/various/chprintf.c
+++ b/os/various/chprintf.c
@@ -73,8 +73,9 @@ static char *ltoa(char *p, long num, unsigned radix) {
 }
 
 #if CHPRINTF_USE_FLOAT
-static long pow10[FLOAT_PRECISION] = {10, 100, 1000, 10000, 100000, 1000000,
-                                      10000000, 100000000, 1000000000};
+static const long pow10[FLOAT_PRECISION] = {
+    10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000
+};
 
 static char *ftoa(char *p, double num, unsigned long precision) {
   long l;