diff --git a/Core/Util/BlockAllocator.cpp b/Core/Util/BlockAllocator.cpp
index 34bf5ee618..1b67b82a9a 100644
--- a/Core/Util/BlockAllocator.cpp
+++ b/Core/Util/BlockAllocator.cpp
@@ -169,7 +169,7 @@ u32 BlockAllocator::AllocAt(u32 position, u32 size, const char *tag)
 	// Upalign size to grain.
 	alignedSize = (alignedSize + grain_ - 1) & ~(grain_ - 1);
 	// Tell the caller the allocated size from their requested starting position.
-	size = alignedSize - (alignedPosition - position);
+	size = alignedSize - (position - alignedPosition);
 
 	Block *bp = GetBlockFromAddress(alignedPosition);
 	if (bp != NULL)