diff --git a/src/numerics/DenseMatrix.cpp b/src/numerics/DenseMatrix.cpp
index 53b84c34cb..046f9a2919 100644
--- a/src/numerics/DenseMatrix.cpp
+++ b/src/numerics/DenseMatrix.cpp
@@ -191,7 +191,7 @@ void multiply(const DenseMatrix& A, const double* const b, double* const prod)
 void increment(const DenseMatrix& A, const double* b, double* prod)
 {
     ct_dgemv(ctlapack::ColMajor, ctlapack::NoTranspose,
-             static_cast<int>(A.nRows()), static_cast<int>(A.nRows()), 1.0,
+             static_cast<int>(A.nRows()), static_cast<int>(A.nColumns()), 1.0,
              A.ptrColumn(0), static_cast<int>(A.nRows()), b, 1, 1.0, prod, 1);
 }
 
diff --git a/test/general/test_matrices.cpp b/test/general/test_matrices.cpp
index b4caa747c2..0d3fd37268 100644
--- a/test/general/test_matrices.cpp
+++ b/test/general/test_matrices.cpp
@@ -179,3 +179,24 @@ TEST_F(DenseMatrixTest, matrix_times_matrix)
     A2.mult(A3, c);
     EXPECT_DOUBLE_EQ(4014, special_sum(c));
 }
+
+TEST_F(DenseMatrixTest, increment)
+{
+    vector_fp c(b1.size(), 3.0);
+    increment(A1, x4.data(), c.data());
+    for (size_t i = 0; i < 4; i++) {
+        EXPECT_DOUBLE_EQ(3.0 + b1[i], c[i]);
+    }
+
+    c.assign(b2.size(), 3.0);
+    increment(A2, x3.data(), c.data());
+    for (size_t i = 0; i < 4; i++) {
+        EXPECT_DOUBLE_EQ(3.0 + b2[i], c[i]);
+    }
+
+    c.assign(b3.size(), 3.0);
+    increment(A3, x4.data(), c.data());
+    for (size_t i = 0; i < 3; i++) {
+        EXPECT_DOUBLE_EQ(3.0 + b3[i], c[i]);
+    }
+}