diff --git a/src/TimeSpan.php b/src/TimeSpan.php
index d48103f..edcabb7 100644
--- a/src/TimeSpan.php
+++ b/src/TimeSpan.php
@@ -48,25 +48,20 @@ public static function fromNanoseconds(int|float $nanoseconds): self
             return new self($nanoseconds);
         }
 
-        $nanoseconds = \sprintf('%.0f', round($nanoseconds));
+        $nanoseconds = round($nanoseconds);
 
-        if ($nanoseconds > 0 && self::comparePositiveNumericStrings($nanoseconds, (string) PHP_INT_MAX) > 0
-            || $nanoseconds < 0 && self::compareNegativeNumericStrings($nanoseconds, (string) PHP_INT_MIN) < 0
-        ) {
+        if (self::isOutOfBounds($nanoseconds)) {
             throw new \OutOfBoundsException('The specified time span cannot be expressed as integer nanoseconds due to overflow.');
         }
 
         return new self((int) $nanoseconds);
     }
 
-    private static function comparePositiveNumericStrings(string $a, string $b): int
+    private static function isOutOfBounds(float $nanoseconds): bool
     {
-        return \strlen($a) <=> \strlen($b) ?: strcmp($a, $b);
-    }
-
-    private static function compareNegativeNumericStrings(string $a, string $b): int
-    {
-        return -(\strlen($a) <=> \strlen($b) ?: strcmp($a, $b));
+        return !is_finite($nanoseconds)
+            || $nanoseconds >= ($bound = 2 ** 63)
+            || $nanoseconds < -$bound;
     }
 
     public static function fromMicroseconds(int|float $microseconds): self
diff --git a/tests/TimeSpanTest.php b/tests/TimeSpanTest.php
index e105c63..e1b7d5a 100644
--- a/tests/TimeSpanTest.php
+++ b/tests/TimeSpanTest.php
@@ -208,6 +208,7 @@ public function testConstructorWithoutArgs(): void
     #[TestWith([100.999_99, 101])]
     #[TestWith([PHP_INT_MAX, PHP_INT_MAX])]
     #[TestWith([PHP_INT_MIN, PHP_INT_MIN])]
+    #[TestWith([PHP_INT_MIN - 1_024, PHP_INT_MIN])]
     #[TestWith([9_223_372_036_854_775_000.0, 9_223_372_036_854_774_784])]
     #[TestWith([-9_223_372_036_854_775_000.0, -9_223_372_036_854_774_784])]
     public function testFromNanoseconds(int|float $nanoseconds, int $expected): void
@@ -322,6 +323,8 @@ public function testFromDaysPHPSince84(float $days, int $expected): void
     #[TestWith([106_751.991_2])]
     #[TestWith([-106_752])]
     #[TestWith([-106_751.991_2])]
+    #[TestWith([NAN])]
+    #[TestWith([INF])]
     public function testFromDaysThrowsOutOfBounds(int|float $days): void
     {
         $this->expectException(\OutOfBoundsException::class);
@@ -330,6 +333,16 @@ public function testFromDaysThrowsOutOfBounds(int|float $days): void
         TimeSpan::fromDays($days);
     }
 
+    #[TestWith([PHP_INT_MAX + 1])]
+    #[TestWith([PHP_INT_MIN - 1_025])]
+    public function testFromNanosecondsThrowsOutOfBounds(float $nanoseconds): void
+    {
+        $this->expectException(\OutOfBoundsException::class);
+        $this->expectExceptionMessage('The specified time span cannot be expressed as integer nanoseconds due to overflow.');
+
+        TimeSpan::fromNanoseconds($nanoseconds);
+    }
+
     #[TestWith([100_000, 100.0, 100])]
     #[TestWith([100_100, 100.1, 100])]
     #[TestWith([100_500, 100.5, 101])]