Convert equality check with 'NaN' to 'isNaN' call

Reports an equality check with Float.NaN or Double.NaN that should be replaced with an isNaN() check.

According to IEEE 754, equality check against NaN always returns false, even for NaN == NaN. Therefore, such a check is likely to be a mistake.

The quick-fix replaces comparison with isNaN() check that uses a different comparison technique and handles NaN values correctly.

Example:

  fun check(value: Double): Boolean {
      return Double.NaN == value
  }

After the fix is applied:

  fun check(value: Double): Boolean {
      return value.isNaN()
  }

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

ConvertNaNEquality

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Kotlin | Probable bugs

Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection ConvertNaNEquality

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

IntelliJ IDEA 2025.2

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.2, Qodana for JVM 2025.2,

Last modified: 18 September 2025