diff --git a/libc/stdio/vfwprintf.cpp b/libc/stdio/vfwprintf.cpp
index 52ae64b..0caeb2d 100644
--- a/libc/stdio/vfwprintf.cpp
+++ b/libc/stdio/vfwprintf.cpp
@@ -510,34 +510,21 @@
         _umax = UARG();
         base = DEC;
         goto nosign;
-      case 'w':
+      case 'w': {
         n = 0;
+        bool fast = false;
         ch = *fmt++;
+        if (ch == 'f') {
+          fast = true;
+          ch = *fmt++;
+        }
         while (is_digit(ch)) {
           APPEND_DIGIT(n, ch);
           ch = *fmt++;
         }
-        switch (n) {
-          case 8: {
-            flags |= CHARINT;
-            goto reswitch;
-          }
-          case 16: {
-            flags |= SHORTINT;
-            goto reswitch;
-          }
-          case 32: {
-            goto reswitch;
-          }
-          case 64: {
-            flags |= LLONGINT;
-            goto reswitch;
-          }
-          default: {
-            __fortify_fatal("%%w%d is unsupported", n);
-            break;
-          }
-        }
+        flags |= helpers::w_to_flag(n, fast);
+        goto reswitch;
+      }
       case 'X':
         xdigs = xdigs_upper;
         goto hex;