diff --git a/source/graphics/LOSTexture.cpp b/source/graphics/LOSTexture.cpp
index 8048b70b7c..107cccd3ab 100644
--- a/source/graphics/LOSTexture.cpp
+++ b/source/graphics/LOSTexture.cpp
@@ -194,9 +194,9 @@ void CLOSTexture::GenerateBitmap(ICmpRangeManager::CLosQuerier los, u8* losData,
 		// Fill in the visibility data
 		for (size_t i = 0; i < w; ++i)
 		{
-			if (los.IsVisible(i, j))
+			if (los.IsVisible_UncheckedRange(i, j))
 				*dataPtr++ = 255;
-			else if (los.IsExplored(i, j))
+			else if (los.IsExplored_UncheckedRange(i, j))
 				*dataPtr++ = 127;
 			else
 				*dataPtr++ = 0;
diff --git a/source/simulation2/components/CCmpRangeManager.cpp b/source/simulation2/components/CCmpRangeManager.cpp
index 67e170398f..eca60942fc 100644
--- a/source/simulation2/components/CCmpRangeManager.cpp
+++ b/source/simulation2/components/CCmpRangeManager.cpp
@@ -1194,7 +1194,7 @@ public:
 				if (!LosIsOffWorld(i, j))
 				{
 					overallVisibleVertices++;
-					exploredVertices += (i32)los.IsExplored(i, j);
+					exploredVertices += (i32)los.IsExplored_UncheckedRange(i, j);
 				}
 			}
 		}
diff --git a/source/simulation2/components/ICmpRangeManager.h b/source/simulation2/components/ICmpRangeManager.h
index 9dcd569b11..03d4ebd9d8 100644
--- a/source/simulation2/components/ICmpRangeManager.h
+++ b/source/simulation2/components/ICmpRangeManager.h
@@ -185,10 +185,40 @@ public:
 	public:
 		/**
 		 * Returns whether the given vertex is visible (i.e. is within a unit's LOS).
-		 * i and j must be in the range [0, verticesPerSide).
 		 */
 		inline bool IsVisible(ssize_t i, ssize_t j)
 		{
+			if (!(i >= 0 && j >= 0 && i < m_VerticesPerSide && j < m_VerticesPerSide))
+				return false;
+
+			// Check high bit of each bit-pair
+			if ((m_Data[j*m_VerticesPerSide + i] & m_PlayerMask) & 0xAAAAAAAAu)
+				return true;
+			else
+				return false;
+		}
+
+		/**
+		 * Returns whether the given vertex is explored (i.e. was (or still is) within a unit's LOS).
+		 */
+		inline bool IsExplored(ssize_t i, ssize_t j)
+		{
+			if (!(i >= 0 && j >= 0 && i < m_VerticesPerSide && j < m_VerticesPerSide))
+				return false;
+
+			// Check low bit of each bit-pair
+			if ((m_Data[j*m_VerticesPerSide + i] & m_PlayerMask) & 0x55555555u)
+				return true;
+			else
+				return false;
+		}
+
+		/**
+		 * Returns whether the given vertex is visible (i.e. is within a unit's LOS).
+		 * i and j must be in the range [0, verticesPerSide), else behaviour is undefined.
+		 */
+		inline bool IsVisible_UncheckedRange(ssize_t i, ssize_t j)
+		{
 #ifndef NDEBUG
 			debug_assert(i >= 0 && j >= 0 && i < m_VerticesPerSide && j < m_VerticesPerSide);
 #endif
@@ -201,9 +231,9 @@ public:
 
 		/**
 		 * Returns whether the given vertex is explored (i.e. was (or still is) within a unit's LOS).
-		 * i and j must be in the range [0, verticesPerSide).
+		 * i and j must be in the range [0, verticesPerSide), else behaviour is undefined.
 		 */
-		inline bool IsExplored(ssize_t i, ssize_t j)
+		inline bool IsExplored_UncheckedRange(ssize_t i, ssize_t j)
 		{
 #ifndef NDEBUG
 			debug_assert(i >= 0 && j >= 0 && i < m_VerticesPerSide && j < m_VerticesPerSide);