diff --git a/examples/jsm/lines/LineMaterial.js b/examples/jsm/lines/LineMaterial.js
index 60cd13dbc2fce8..856bb8f499ffc5 100644
--- a/examples/jsm/lines/LineMaterial.js
+++ b/examples/jsm/lines/LineMaterial.js
@@ -77,7 +77,10 @@ ShaderLib[ 'line' ] = {
 			// conservative estimate of the near plane
 			float a = projectionMatrix[ 2 ][ 2 ]; // 3nd entry in 3th column
 			float b = projectionMatrix[ 3 ][ 2 ]; // 3nd entry in 4th column
-			float nearEstimate = - 0.5 * b / a;
+			
+			// we need different nearEstimate formula for reversed and default depth buffer
+			// a is positive with a reversed depth buffer so it can be used for controlling the code flow
+			float nearEstimate = ( a > 0.0 ) ? ( - b / ( a + 1.0 ) ) : ( - 0.5 * b / a );
 
 			float alpha = ( nearEstimate - start.z ) / ( end.z - start.z );
 
diff --git a/src/materials/nodes/Line2NodeMaterial.js b/src/materials/nodes/Line2NodeMaterial.js
index e53129fa3d1fa3..65d1cd0a911a5d 100644
--- a/src/materials/nodes/Line2NodeMaterial.js
+++ b/src/materials/nodes/Line2NodeMaterial.js
@@ -141,7 +141,11 @@ class Line2NodeMaterial extends NodeMaterial {
 
 			const a = cameraProjectionMatrix.element( 2 ).element( 2 ); // 3nd entry in 3th column
 			const b = cameraProjectionMatrix.element( 3 ).element( 2 ); // 3nd entry in 4th column
-			const nearEstimate = b.mul( - 0.5 ).div( a );
+
+			// we need different nearEstimate formula for reversed and default depth buffer
+			// a is positive with a reversed depth buffer so it can be used for controlling the code flow
+
+			const nearEstimate = a.greaterThan( 0 ).select( b.negate().div( a.add( 1 ) ), b.mul( - 0.5 ).div( a ) );
 
 			const alpha = nearEstimate.sub( start.z ).div( end.z.sub( start.z ) );