diff --git a/src/nvimage/Filter.cpp b/src/nvimage/Filter.cpp
index b1be2b4..8edddfa 100644
--- a/src/nvimage/Filter.cpp
+++ b/src/nvimage/Filter.cpp
@@ -503,7 +503,7 @@ void Kernel2::initBlendedSobel(const Vector4 & scale)
 
 		for (int i = 0; i < 7; i++) {
 			for (int e = 0; e < 7; e++) {
-				m_data[i * 9 + e + 1] += elements[i * 7 + e] * scale.z();
+				m_data[(i + 1) * 9 + e + 1] += elements[i * 7 + e] * scale.z();
 			}
 		}
 	}
@@ -518,7 +518,7 @@ void Kernel2::initBlendedSobel(const Vector4 & scale)
 
 		for (int i = 0; i < 5; i++) {
 			for (int e = 0; e < 5; e++) {
-				m_data[i * 9 + e + 2] += elements[i * 5 + e] * scale.y();
+				m_data[(i + 2) * 9 + e + 2] += elements[i * 5 + e] * scale.y();
 			}
 		}
 	}
@@ -531,7 +531,7 @@ void Kernel2::initBlendedSobel(const Vector4 & scale)
 
 		for (int i = 0; i < 3; i++) {
 			for (int e = 0; e < 3; e++) {
-				m_data[i * 9 + e + 3] += elements[i * 3 + e] * scale.x();
+				m_data[(i + 3) * 9 + e + 3] += elements[i * 3 + e] * scale.x();
 			}
 		}
 	}