diff --git a/trend/smma.go b/trend/smma.go
index a532f06..4519815 100644
--- a/trend/smma.go
+++ b/trend/smma.go
@@ -57,7 +57,7 @@ func (s *Smma[T]) Compute(c <-chan T) <-chan T {
 		result <- before
 
 		for n := range c {
-			before = ((before*T(s.Period) - 1) + n) / T(s.Period)
+			before = ((before * (T(s.Period) - 1)) + n) / T(s.Period)
 			result <- before
 		}
 	}()
diff --git a/trend/testdata/smma.csv b/trend/testdata/smma.csv
index fe7166c..8d0a392 100644
--- a/trend/testdata/smma.csv
+++ b/trend/testdata/smma.csv
@@ -6,247 +6,247 @@ Close,Smma
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