diff --git a/test/chan/powser1.go b/test/chan/powser1.go
index 5357eec50f..e999dde2be 100644
--- a/test/chan/powser1.go
+++ b/test/chan/powser1.go
@@ -595,7 +595,7 @@ func Subst(U, V PS) PS {
 	return Z
 }
 
-// Monomial Substition: U(c x^n)
+// Monomial Substitution: U(c x^n)
 // Each Ui is multiplied by c^i and followed by n-1 zeros
 
 func MonSubst(U PS, c0 rat, n int) PS {
diff --git a/test/chan/powser2.go b/test/chan/powser2.go
index fb1fb8518e..72cbba8cf6 100644
--- a/test/chan/powser2.go
+++ b/test/chan/powser2.go
@@ -609,7 +609,7 @@ func Subst(U, V PS) PS {
 	return Z
 }
 
-// Monomial Substition: U(c x^n)
+// Monomial Substitution: U(c x^n)
 // Each Ui is multiplied by c^i and followed by n-1 zeros
 
 func MonSubst(U PS, c0 *rat, n int) PS {