diff --git a/src/nodebuild.cpp b/src/nodebuild.cpp
index d4794c639..5b849687c 100644
--- a/src/nodebuild.cpp
+++ b/src/nodebuild.cpp
@@ -814,8 +814,8 @@ void FNodeBuilder::SplitSegs (uint32_t set, node_t &node, uint32_t splitseg, uin
 			frac = InterceptVector (node, *seg);
 			newvert.x = Vertices[seg->v1].x;
 			newvert.y = Vertices[seg->v1].y;
-			newvert.x += fixed_t(frac * double(Vertices[seg->v2].x - newvert.x));
-			newvert.y += fixed_t(frac * double(Vertices[seg->v2].y - newvert.y));
+			newvert.x += fixed_t(frac * (double(Vertices[seg->v2].x) - newvert.x));
+			newvert.y += fixed_t(frac * (double(Vertices[seg->v2].y) - newvert.y));
 			vertnum = VertexMap->SelectVertexClose (newvert);
 
 			if (vertnum != (unsigned int)seg->v1 && vertnum != (unsigned int)seg->v2)
diff --git a/src/nodebuild.h b/src/nodebuild.h
index f66e64aa4..fd943cbbd 100644
--- a/src/nodebuild.h
+++ b/src/nodebuild.h
@@ -91,6 +91,8 @@ struct FSimpleVert
 	fixed_t x, y;
 };
 
+typedef int64_t fixed64_t;
+
 class FNodeBuilder
 {
 	struct FPrivSeg
@@ -167,14 +169,14 @@ class FNodeBuilder
 		FNodeBuilder &MyBuilder;
 		TArray<int> *VertexGrid;
 
-		fixed_t MinX, MinY, MaxX, MaxY;
+		fixed64_t MinX, MinY, MaxX, MaxY;
 		int BlocksWide, BlocksTall;
 
 		enum { BLOCK_SHIFT = 8 + FRACBITS };
 		enum { BLOCK_SIZE = 1 << BLOCK_SHIFT };
 
 		int InsertVertex (FPrivVert &vert);
-		inline int GetBlock (fixed_t x, fixed_t y)
+		inline int GetBlock (fixed64_t x, fixed64_t y)
 		{
 			assert (x >= MinX);
 			assert (y >= MinY);
diff --git a/src/nodebuild_utility.cpp b/src/nodebuild_utility.cpp
index 754e3519c..9dd3c7786 100644
--- a/src/nodebuild_utility.cpp
+++ b/src/nodebuild_utility.cpp
@@ -641,8 +641,8 @@ FNodeBuilder::FVertexMap::FVertexMap (FNodeBuilder &builder,
 	MinY = miny;
 	BlocksWide = int(((double(maxx) - minx + 1) + (BLOCK_SIZE - 1)) / BLOCK_SIZE);
 	BlocksTall = int(((double(maxy) - miny + 1) + (BLOCK_SIZE - 1)) / BLOCK_SIZE);
-	MaxX = MinX + BlocksWide * BLOCK_SIZE - 1;
-	MaxY = MinY + BlocksTall * BLOCK_SIZE - 1;
+	MaxX = MinX + fixed64_t(BlocksWide) * BLOCK_SIZE - 1;
+	MaxY = MinY + fixed64_t(BlocksTall) * BLOCK_SIZE - 1;
 	VertexGrid = new TArray<int>[BlocksWide * BlocksTall];
 }
 
@@ -703,10 +703,10 @@ int FNodeBuilder::FVertexMap::InsertVertex (FNodeBuilder::FPrivVert &vert)
 	// If a vertex is near a block boundary, then it will be inserted on
 	// both sides of the boundary so that SelectVertexClose can find
 	// it by checking in only one block.
-	fixed_t minx = MAX (MinX, vert.x - VERTEX_EPSILON);
-	fixed_t maxx = MIN (MaxX, vert.x + VERTEX_EPSILON);
-	fixed_t miny = MAX (MinY, vert.y - VERTEX_EPSILON);
-	fixed_t maxy = MIN (MaxY, vert.y + VERTEX_EPSILON);
+	fixed64_t minx = MAX (MinX, fixed64_t(vert.x) - VERTEX_EPSILON);
+	fixed64_t maxx = MIN (MaxX, fixed64_t(vert.x) + VERTEX_EPSILON);
+	fixed64_t miny = MAX (MinY, fixed64_t(vert.y) - VERTEX_EPSILON);
+	fixed64_t maxy = MIN (MaxY, fixed64_t(vert.y) + VERTEX_EPSILON);
 
 	int blk[4] =
 	{