diff --git a/libc/stdio/vfwscanf.cpp b/libc/stdio/vfwscanf.cpp
index 14b1754..3df4a87 100644
--- a/libc/stdio/vfwscanf.cpp
+++ b/libc/stdio/vfwscanf.cpp
@@ -223,6 +223,10 @@
         int size = 0;
         bool fast = false;
         c = *fmt++;
+        if (c == 'f') {
+          fast = true;
+          c = *fmt++;
+        }
         while (is_digit(c)) {
           APPEND_DIGIT(size, c);
           c = *fmt++;