diff --git a/library/core/tests/num/int_macros.rs b/library/core/tests/num/int_macros.rs
index 439bbe66997..a9ce8433864 100644
--- a/library/core/tests/num/int_macros.rs
+++ b/library/core/tests/num/int_macros.rs
@@ -290,6 +290,17 @@ macro_rules! int_module {
                 assert_eq!(r.saturating_pow(0), 1 as $T);
             }
 
+            #[test]
+            fn test_isqrt() {
+                assert_eq!($T::MIN.checked_isqrt(), None);
+                assert_eq!((-1 as $T).checked_isqrt(), None);
+                assert_eq!((0 as $T).isqrt(), 0 as $T);
+                assert_eq!((1 as $T).isqrt(), 1 as $T);
+                assert_eq!((2 as $T).isqrt(), 1 as $T);
+                assert_eq!((99 as $T).isqrt(), 9 as $T);
+                assert_eq!((100 as $T).isqrt(), 10 as $T);
+            }
+
             #[test]
             fn test_div_floor() {
                 let a: $T = 8;
diff --git a/library/core/tests/num/uint_macros.rs b/library/core/tests/num/uint_macros.rs
index 7d6203db0b9..9a8421c7b95 100644
--- a/library/core/tests/num/uint_macros.rs
+++ b/library/core/tests/num/uint_macros.rs
@@ -206,6 +206,16 @@ macro_rules! uint_module {
                 assert_eq!(r.saturating_pow(2), MAX);
             }
 
+            #[test]
+            fn test_isqrt() {
+                assert_eq!((0 as $T).isqrt(), 0 as $T);
+                assert_eq!((1 as $T).isqrt(), 1 as $T);
+                assert_eq!((2 as $T).isqrt(), 1 as $T);
+                assert_eq!((99 as $T).isqrt(), 9 as $T);
+                assert_eq!((100 as $T).isqrt(), 10 as $T);
+                assert_eq!($T::MAX.isqrt(), (1 << ($T::BITS / 2)) - 1);
+            }
+
             #[test]
             fn test_div_floor() {
                 assert_eq!((8 as $T).div_floor(3), 2);