diff --git a/library/core/benches/num/int_log/mod.rs b/library/core/benches/num/int_log/mod.rs
index 542a0a0ca08..6a219bcdd55 100644
--- a/library/core/benches/num/int_log/mod.rs
+++ b/library/core/benches/num/int_log/mod.rs
@@ -1,5 +1,3 @@
-#![feature(int_log)]
-
 use rand::Rng;
 use test::{black_box, Bencher};
 
diff --git a/library/core/src/num/int_log10.rs b/library/core/src/num/int_log10.rs
index d28552cf4aa..398bb07a07e 100644
--- a/library/core/src/num/int_log10.rs
+++ b/library/core/src/num/int_log10.rs
@@ -7,16 +7,16 @@ mod unchecked {
         // in the bits above the low 8 bits.
 
         // Adding c1 to val gives 10 in the top bits for val < 10, 11 for val >= 10
-        let c1 = 0b11_00000000 - 10; // 758
+        const C1: u32 = 0b11_00000000 - 10; // 758
         // Adding c2 to val gives 01 in the top bits for val < 100, 10 for val >= 100
-        let c2 = 0b10_00000000 - 100; // 412
+        const C2: u32 = 0b10_00000000 - 100; // 412
 
         // Value of top bits:
         //            +c1  +c2  1&2
         //     0..=9   10   01   00 = 0
         //   10..=99   11   01   01 = 1
         // 100..=255   11   10   10 = 2
-        ((val + c1) & (val + c2)) >> 8
+        ((val + C1) & (val + C2)) >> 8
     }
 
     // 0 < val < 100_000
@@ -24,10 +24,10 @@ mod unchecked {
         // Similar to u8, when adding one of these constants to val,
         // we get two possible bit patterns above the low 17 bits,
         // depending on whether val is below or above the threshold.
-        let c1 = 0b011_00000000000000000 - 10; // 393206
-        let c2 = 0b100_00000000000000000 - 100; // 524188
-        let c3 = 0b111_00000000000000000 - 1000; // 916504
-        let c4 = 0b100_00000000000000000 - 10000; // 514288
+        const C1: u32 = 0b011_00000000000000000 - 10; // 393206
+        const C2: u32 = 0b100_00000000000000000 - 100; // 524188
+        const C3: u32 = 0b111_00000000000000000 - 1000; // 916504
+        const C4: u32 = 0b100_00000000000000000 - 10000; // 514288
 
         // Value of top bits:
         //                +c1  +c2  1&2  +c3  +c4  3&4   ^
@@ -36,7 +36,7 @@ mod unchecked {
         //     100..=999  011  100  000  110  011  010  010 = 2
         //   1000..=9999  011  100  000  111  011  011  011 = 3
         // 10000..=99999  011  100  000  111  100  100  100 = 4
-        (((val + c1) & (val + c2)) ^ ((val + c3) & (val + c4))) >> 17
+        (((val + C1) & (val + C2)) ^ ((val + C3) & (val + C4))) >> 17
     }
 
     // 0 < val <= u16::MAX