diff --git a/pkg/apis/pipeline/v1/matrix_types.go b/pkg/apis/pipeline/v1/matrix_types.go
index 6ae8142a9b2..8c18f917dc3 100644
--- a/pkg/apis/pipeline/v1/matrix_types.go
+++ b/pkg/apis/pipeline/v1/matrix_types.go
@@ -72,7 +72,7 @@ func (m *Matrix) FanOut() []Params {
 	for _, parameter := range m.Params {
 		combinations = combinations.fanOutMatrixParams(parameter)
 	}
-	combinations = combinations.overwriteCombinations(includeCombinations)
+	combinations.overwriteCombinations(includeCombinations)
 	combinations = combinations.addNewCombinations(includeCombinations)
 	return combinations.toParams()
 }
@@ -84,7 +84,11 @@ func (cs Combinations) overwriteCombinations(ics Combinations) Combinations {
 	for _, paramCombination := range cs {
 		for _, includeCombination := range ics {
 			if paramCombination.contains(includeCombination) {
-				includeCombination.overwrite(paramCombination)
+				// overwrite the parameter name and value in existing combination
+				// with the include combination
+				for name, val := range includeCombination {
+					paramCombination[name] = val
+				}
 			}
 		}
 	}
@@ -115,14 +119,6 @@ func (c Combination) contains(includeCombination Combination) bool {
 	return true
 }
 
-// overwrite the parameter name and value exists in combination with the include combination
-func (c Combination) overwrite(oldCombination Combination) Combination {
-	for name, val := range c {
-		oldCombination[name] = val
-	}
-	return oldCombination
-}
-
 // shouldAddNewCombination returns true if the include parameter name exists but the value is
 // missing from combinations
 func (cs Combinations) shouldAddNewCombination(includeCombination map[string]string) bool {
diff --git a/pkg/apis/pipeline/v1beta1/matrix_types.go b/pkg/apis/pipeline/v1beta1/matrix_types.go
index 9b322fe6084..5c67de4e979 100644
--- a/pkg/apis/pipeline/v1beta1/matrix_types.go
+++ b/pkg/apis/pipeline/v1beta1/matrix_types.go
@@ -72,7 +72,7 @@ func (m *Matrix) FanOut() []Params {
 	for _, parameter := range m.Params {
 		combinations = combinations.fanOutMatrixParams(parameter)
 	}
-	combinations = combinations.overwriteCombinations(includeCombinations)
+	combinations.overwriteCombinations(includeCombinations)
 	combinations = combinations.addNewCombinations(includeCombinations)
 	return combinations.toParams()
 }
@@ -84,7 +84,11 @@ func (cs Combinations) overwriteCombinations(ics Combinations) Combinations {
 	for _, paramCombination := range cs {
 		for _, includeCombination := range ics {
 			if paramCombination.contains(includeCombination) {
-				includeCombination.overwrite(paramCombination)
+				// overwrite the parameter name and value in existing combination
+				// with the include combination
+				for name, val := range includeCombination {
+					paramCombination[name] = val
+				}
 			}
 		}
 	}
@@ -115,14 +119,6 @@ func (c Combination) contains(includeCombination Combination) bool {
 	return true
 }
 
-// overwrite the parameter name and value exists in combination with the include combination
-func (c Combination) overwrite(oldCombination Combination) Combination {
-	for name, val := range c {
-		oldCombination[name] = val
-	}
-	return oldCombination
-}
-
 // shouldAddNewCombination returns true if the include parameter name exists but the value is
 // missing from combinations
 func (cs Combinations) shouldAddNewCombination(includeCombination map[string]string) bool {