Index: uspace/lib/c/generic/io/printf_core.c
===================================================================
--- uspace/lib/c/generic/io/printf_core.c	(revision b639d569d5f3a960f411e38bd76a17acdb0cda5f)
+++ uspace/lib/c/generic/io/printf_core.c	(revision ce55b43d2fde4827af9a50d151005ef2e652cb21)
@@ -114,5 +114,6 @@
 	PrintfQualifierLongLong,
 	PrintfQualifierPointer,
-	PrintfQualifierSize
+	PrintfQualifierSize,
+	PrintfQualifierMax
 } qualifier_t;
 
@@ -1484,4 +1485,9 @@
 				uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
 				break;
+			case 'j':
+				qualifier = PrintfQualifierMax;
+				i = nxt;
+				uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
+				break;
 			default:
 				/* Default type */
@@ -1629,4 +1635,8 @@
 				number = (uint64_t) va_arg(ap, size_t);
 				break;
+			case PrintfQualifierMax:
+				size = sizeof(uintmax_t);
+				number = (uint64_t) va_arg(ap, uintmax_t);
+				break;
 			default:
 				/* Unknown qualifier */