diff --git a/Source/Core/QuantizedMeshTerrainData.js b/Source/Core/QuantizedMeshTerrainData.js
index 00cf63cbbcc1..6d2f4a737156 100644
--- a/Source/Core/QuantizedMeshTerrainData.js
+++ b/Source/Core/QuantizedMeshTerrainData.js
@@ -501,17 +501,17 @@ define([
     function isPointInsideUVTriangle(u, v, u0, v0, u1, v1, u2, v2) {
         var inside = false;
 
-        var intersect = ((v0 > v) !== (v1 > v)) && (u < (u1 - u0) * (v - v0) / (v1 - v0) + u0);
+        var intersect = ((v0 > v) !== (v1 >= v)) && (u <= (u1 - u0) * (v - v0) / (v1 - v0) + u0);
         if (intersect) {
             inside = !inside;
         }
 
-        intersect = ((v1 > v) !== (v2 > v)) && (u < (u2 - u1) * (v - v1) / (v2 - v1) + u1);
+        intersect = ((v1 > v) !== (v2 >= v)) && (u <= (u2 - u1) * (v - v1) / (v2 - v1) + u1);
         if (intersect) {
             inside = !inside;
         }
 
-        intersect = ((v2 > v) !== (v0 > v)) && (u < (u0 - u2) * (v - v2) / (v0 - v2) + u2);
+        intersect = ((v2 > v) !== (v0 >= v)) && (u <= (u0 - u2) * (v - v2) / (v0 - v2) + u2);
         if (intersect) {
             inside = !inside;
         }
diff --git a/Specs/Core/sampleTerrainMostDetailedSpec.js b/Specs/Core/sampleTerrainMostDetailedSpec.js
index b85013ead263..a6a1eaad0ac0 100644
--- a/Specs/Core/sampleTerrainMostDetailedSpec.js
+++ b/Specs/Core/sampleTerrainMostDetailedSpec.js
@@ -74,7 +74,7 @@ defineSuite([
     });
 
     it('works for a dodgy point right near the edge of a tile', function() {
-        var positions = [new Cartographic(0.33179290856829535, 0.7363107781851076)];
+        var positions = [new Cartographic(0.33179290856829535, 0.7363107781851078)];
 
         return sampleTerrainMostDetailed(worldTerrain, positions).then(function() {
             expect(positions[0].height).toBeDefined();
diff --git a/Specs/Core/sampleTerrainSpec.js b/Specs/Core/sampleTerrainSpec.js
index 7d69157ffa02..a11d19359e9d 100644
--- a/Specs/Core/sampleTerrainSpec.js
+++ b/Specs/Core/sampleTerrainSpec.js
@@ -93,7 +93,7 @@ defineSuite([
     });
 
     it('works for a dodgy point right near the edge of a tile', function() {
-        var positions = [new Cartographic(0.33179290856829535, 0.7363107781851076)];
+        var positions = [new Cartographic(0.33179290856829535, 0.7363107781851078)];
 
         return sampleTerrain(worldTerrain, 12, positions).then(function() {
             expect(positions[0].height).toBeDefined();