diff --git a/lib/libc/printf.c b/lib/libc/printf.c
index 45e153e..0def148 100644
--- a/lib/libc/printf.c
+++ b/lib/libc/printf.c
@@ -9,8 +9,6 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include <common/debug.h>
-
 #define get_num_va_args(_args, _lcount)				\
 	(((_lcount) > 1)  ? va_arg(_args, long long int) :	\
 	(((_lcount) == 1) ? va_arg(_args, long int) :		\
@@ -43,6 +41,12 @@
 	int i = 0, count = 0;
 	unsigned int rem;
 
+	/* num_buf is only large enough for radix >= 10 */
+	if (radix < 10) {
+		assert(0);
+		return 0;
+	}
+
 	do {
 		rem = unum % radix;
 		if (rem < 0xa)