diff --git a/kmath-complex/src/commonMain/kotlin/space/kscience/kmath/complex/Complex.kt b/kmath-complex/src/commonMain/kotlin/space/kscience/kmath/complex/Complex.kt
index d3c414838..77fe782a9 100644
--- a/kmath-complex/src/commonMain/kotlin/space/kscience/kmath/complex/Complex.kt
+++ b/kmath-complex/src/commonMain/kotlin/space/kscience/kmath/complex/Complex.kt
@@ -41,7 +41,7 @@ public val Complex.r: Double
  * An angle between vector represented by complex number and X axis.
  */
 public val Complex.theta: Double
-    get() = atan(im / re)
+    get() = atan2(im, re)
 
 private val PI_DIV_2 = Complex(PI / 2, 0)