diff --git a/src/encoding/ascii85/ascii85.go b/src/encoding/ascii85/ascii85.go
index d42eb0ab00a..f1f7af863c3 100644
--- a/src/encoding/ascii85/ascii85.go
+++ b/src/encoding/ascii85/ascii85.go
@@ -142,9 +142,7 @@ func (e *encoder) Write(p []byte) (n int, err error) {
 	}
 
 	// Trailing fringe.
-	for i := 0; i < len(p); i++ {
-		e.buf[i] = p[i]
-	}
+	copy(e.buf[:], p)
 	e.nbuf = len(p)
 	n += len(p)
 	return
diff --git a/src/encoding/base32/base32.go b/src/encoding/base32/base32.go
index 2f7d3637e5a..3feea9ba473 100644
--- a/src/encoding/base32/base32.go
+++ b/src/encoding/base32/base32.go
@@ -221,9 +221,7 @@ func (e *encoder) Write(p []byte) (n int, err error) {
 	}
 
 	// Trailing fringe.
-	for i := 0; i < len(p); i++ {
-		e.buf[i] = p[i]
-	}
+	copy(e.buf[:], p)
 	e.nbuf = len(p)
 	n += len(p)
 	return
diff --git a/src/encoding/base64/base64.go b/src/encoding/base64/base64.go
index 0c33f8e5f84..4a3e590649e 100644
--- a/src/encoding/base64/base64.go
+++ b/src/encoding/base64/base64.go
@@ -229,9 +229,7 @@ func (e *encoder) Write(p []byte) (n int, err error) {
 	}
 
 	// Trailing fringe.
-	for i := 0; i < len(p); i++ {
-		e.buf[i] = p[i]
-	}
+	copy(e.buf[:], p)
 	e.nbuf = len(p)
 	n += len(p)
 	return