diff --git a/spine-c/src/spine/Animation.c b/spine-c/src/spine/Animation.c
index 6d7732863..65efdd419 100644
--- a/spine-c/src/spine/Animation.c
+++ b/spine-c/src/spine/Animation.c
@@ -664,14 +664,14 @@ void _spFFDTimeline_apply (const spTimeline* timeline, spSkeleton* skeleton, flo
 		return; /* Time is before first frame. */
 	}
 
-	if (slot->attachmentVerticesCount != self->frameVerticesCount) alpha = 1; /* Don't mix from uninitialized slot vertices. */
 	if (slot->attachmentVerticesCount < self->frameVerticesCount) {
 		if (slot->attachmentVerticesCapacity < self->frameVerticesCount) {
 			FREE(slot->attachmentVertices);
 			slot->attachmentVertices = MALLOC(float, self->frameVerticesCount);
 			slot->attachmentVerticesCapacity = self->frameVerticesCount;
 		}
-	}
+	} else if (slot->attachmentVerticesCount > self->frameVerticesCount)
+		alpha = 1; /* Don't mix from uninitialized slot vertices. */
 	slot->attachmentVerticesCount = self->frameVerticesCount;
 
 	if (time >= self->frames[self->framesCount - 1]) {
diff --git a/spine-csharp/src/Animation.cs b/spine-csharp/src/Animation.cs
index 278b5d99d..8b4a08a81 100644
--- a/spine-csharp/src/Animation.cs
+++ b/spine-csharp/src/Animation.cs
@@ -580,18 +580,20 @@ namespace Spine {
 			int vertexCount = frameVertices[0].Length;
 
 			float[] vertices = slot.attachmentVertices;
-			if (vertices.Length != vertexCount) alpha = 1; // Don't mix from uninitialized slot vertices.
 			if (vertices.Length < vertexCount) {
 				vertices = new float[vertexCount];
 				slot.attachmentVertices = vertices;
-			}
+			} else if (vertices.Length > vertexCount)
+				alpha = 1; // Don't mix from uninitialized slot vertices.
 			slot.attachmentVerticesCount = vertexCount;
 
 			if (time >= frames[frames.Length - 1]) { // Time is after last frame.
 				float[] lastVertices = frameVertices[frames.Length - 1];
 				if (alpha < 1) {
-					for (int i = 0; i < vertexCount; i++)
-						vertices[i] += (lastVertices[i] - vertices[i]) * alpha;
+					for (int i = 0; i < vertexCount; i++) {
+						float vertex = vertices[i];
+						vertices[i] = vertex + (lastVertices[i] - vertex) * alpha;
+					}
 				} else
 					Array.Copy(lastVertices, 0, vertices, 0, vertexCount);
 				return;
@@ -609,7 +611,8 @@ namespace Spine {
 			if (alpha < 1) {
 				for (int i = 0; i < vertexCount; i++) {
 					float prev = prevVertices[i];
-					vertices[i] += (prev + (nextVertices[i] - prev) * percent - vertices[i]) * alpha;
+					float vertex = vertices[i];
+					vertices[i] = vertex + (prev + (nextVertices[i] - prev) * percent - vertex) * alpha;
 				}
 			} else {
 				for (int i = 0; i < vertexCount; i++) {
diff --git a/spine-csharp/src/Bone.cs b/spine-csharp/src/Bone.cs
index 1e1974cda..86546b2cd 100644
--- a/spine-csharp/src/Bone.cs
+++ b/spine-csharp/src/Bone.cs
@@ -85,7 +85,6 @@ namespace Spine {
 		/// <summary>Computes the world SRT using the parent bone and the local SRT.</summary>
 		public void UpdateWorldTransform () {
 			Bone parent = this.parent;
-			Skeleton skeleton = this.skeleton;
 			float x = this.x, y = this.y;
 			if (parent != null) {
 				worldX = x * parent.m00 + y * parent.m01 + parent.worldX;
@@ -98,17 +97,18 @@ namespace Spine {
 					worldScaleY = scaleY;
 				}
 				worldRotation = data.inheritRotation ? parent.worldRotation + rotationIK : rotationIK;
-				worldFlipX = parent.worldFlipX ^ flipX;
-				worldFlipY = parent.worldFlipY ^ flipY;
+				worldFlipX = parent.worldFlipX != flipX;
+				worldFlipY = parent.worldFlipY != flipY;
 			} else {
+				Skeleton skeleton = this.skeleton;
 				bool skeletonFlipX = skeleton.flipX, skeletonFlipY = skeleton.flipY;
 				worldX = skeletonFlipX ? -x : x;
 				worldY = skeletonFlipY != yDown ? -y : y;
 				worldScaleX = scaleX;
 				worldScaleY = scaleY;
 				worldRotation = rotationIK;
-				worldFlipX = skeletonFlipX ^ flipX;
-				worldFlipY = skeletonFlipY ^ flipY;
+				worldFlipX = skeletonFlipX != flipX;
+				worldFlipY = skeletonFlipY != flipY;
 			}
 			float radians = worldRotation * (float)Math.PI / 180;
 			float cos = (float)Math.Cos(radians);