diff --git a/plonky2/src/gates/base_sum.rs b/plonky2/src/gates/base_sum.rs
index 43ae2fd2..93ac7e8d 100644
--- a/plonky2/src/gates/base_sum.rs
+++ b/plonky2/src/gates/base_sum.rs
@@ -34,7 +34,7 @@ impl<const B: usize> BaseSumGate<B> {
 
     pub fn new_from_config<F: Field64>(config: &CircuitConfig) -> Self {
         let num_limbs =
-            log_floor(F::ORDER as usize, B).min(config.num_routed_wires - Self::START_LIMBS);
+            log_floor(F::ORDER as usize - 1, B).min(config.num_routed_wires - Self::START_LIMBS);
         Self::new(num_limbs)
     }
 
diff --git a/util/src/lib.rs b/util/src/lib.rs
index 33fe7ab4..3136a4b2 100644
--- a/util/src/lib.rs
+++ b/util/src/lib.rs
@@ -38,7 +38,7 @@ pub fn log2_strict(n: usize) -> usize {
     res as usize
 }
 
-/// Returns the largest `i` such that `base**i < n`.
+/// Returns the largest integer `i` such that `base**i <= n`.
 pub const fn log_floor(n: usize, base: usize) -> usize {
     assert!(n > 0);
     assert!(base > 1);
@@ -46,7 +46,7 @@ pub const fn log_floor(n: usize, base: usize) -> usize {
     let mut cur: usize = 1;
     loop {
         let (mul, overflow) = cur.overflowing_mul(base);
-        if overflow || mul >= n {
+        if overflow || mul > n {
             return i;
         } else {
             i += 1;