diff --git a/include/fast_float/ascii_number.h b/include/fast_float/ascii_number.h
index 6c79509..371f3da 100644
--- a/include/fast_float/ascii_number.h
+++ b/include/fast_float/ascii_number.h
@@ -294,6 +294,17 @@ loop_parse_if_eight_digits(char const *&p, char const *const pend,
             p)); // in rare cases, this will overflow, but that's ok
     p += 8;
   }
+  // 4-digit SWAR follow-up (ported from ffc EXP-001): consume a remaining 4-7
+  // digit run in one step rather than byte-by-byte. GCC path only — on Clang
+  // the follow-up's presence bloated the 2x-unroll codegen and regressed random.
+  if ((pend - p) >= 4) {
+    uint32_t const val4 = read4_to_u32(p);
+    if (is_made_of_four_digits_fast(val4)) {
+      i = i * 10000 +
+          parse_four_digits_unrolled(val4); // in rare cases overflows, that's ok
+      p += 4;
+    }
+  }
 #endif
 }