diff --git a/pgtype/testutil/testutil.go b/pgtype/testutil/testutil.go
index 462549a7..3711381c 100644
--- a/pgtype/testutil/testutil.go
+++ b/pgtype/testutil/testutil.go
@@ -107,7 +107,7 @@ func TestPgxSuccessfulTranscodeEqFunc(t testing.TB, pgTypeName string, values []
 	conn := MustConnectPgx(t)
 	defer MustCloseContext(t, conn)
 
-	ps, err := conn.Prepare("test", fmt.Sprintf("select $1::%s", pgTypeName))
+	_, err := conn.Prepare("test", fmt.Sprintf("select $1::%s", pgTypeName))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -121,29 +121,43 @@ func TestPgxSuccessfulTranscodeEqFunc(t testing.TB, pgTypeName string, values []
 	}
 
 	for i, v := range values {
-		for _, fc := range formats {
-			ps.FieldDescriptions[0].FormatCode = fc.formatCode
-			vEncoder := ForceEncoder(v, fc.formatCode)
-			if vEncoder == nil {
-				t.Logf("Skipping: %#v does not implement %v", v, fc.name)
-				continue
-			}
-			// Derefence value if it is a pointer
-			derefV := v
-			refVal := reflect.ValueOf(v)
-			if refVal.Kind() == reflect.Ptr {
-				derefV = refVal.Elem().Interface()
-			}
+		for _, paramFormat := range formats {
+			for _, resultFormat := range formats {
+				vEncoder := ForceEncoder(v, paramFormat.formatCode)
+				if vEncoder == nil {
+					t.Logf("Skipping Param %s Result %s: %#v does not implement %v for encoding", paramFormat.name, resultFormat.name, v, paramFormat.name)
+					continue
+				}
+				switch resultFormat.formatCode {
+				case pgx.TextFormatCode:
+					if _, ok := v.(pgtype.TextEncoder); !ok {
+						t.Logf("Skipping Param %s Result %s: %#v does not implement %v for decoding", paramFormat.name, resultFormat.name, v, resultFormat.name)
+						continue
+					}
+				case pgx.BinaryFormatCode:
+					if _, ok := v.(pgtype.BinaryEncoder); !ok {
+						t.Logf("Skipping Param %s Result %s: %#v does not implement %v for decoding", paramFormat.name, resultFormat.name, v, resultFormat.name)
+						continue
+					}
+				}
 
-			result := reflect.New(reflect.TypeOf(derefV))
+				// Derefence value if it is a pointer
+				derefV := v
+				refVal := reflect.ValueOf(v)
+				if refVal.Kind() == reflect.Ptr {
+					derefV = refVal.Elem().Interface()
+				}
 
-			err := conn.QueryRow(context.Background(), "test", vEncoder).Scan(result.Interface())
-			if err != nil {
-				t.Errorf("%v %d: %v", fc.name, i, err)
-			}
+				result := reflect.New(reflect.TypeOf(derefV))
 
-			if !eqFunc(result.Elem().Interface(), derefV) {
-				t.Errorf("%v %d: expected %v, got %v", fc.name, i, derefV, result.Elem().Interface())
+				err := conn.QueryRow(context.Background(), "test", pgx.QueryResultFormats{resultFormat.formatCode}, vEncoder).Scan(result.Interface())
+				if err != nil {
+					t.Errorf("Param %s Result %s %d: %v", paramFormat.name, resultFormat.name, i, err)
+				}
+
+				if !eqFunc(result.Elem().Interface(), derefV) {
+					t.Errorf("Param %s Result %s %d: expected %v, got %v", paramFormat.name, resultFormat.name, i, derefV, result.Elem().Interface())
+				}
 			}
 		}
 	}