diff --git a/internal/sanitize/sanitize.go b/internal/sanitize/sanitize.go
index 173523d95..e0ae9bedb 100644
--- a/internal/sanitize/sanitize.go
+++ b/internal/sanitize/sanitize.go
@@ -151,7 +151,7 @@ func QuoteString(dst []byte, str string) []byte {
 
 	dst = append(dst, quote...)
 
-	p := slices.Grow(dst[len(dst):], len(str)+2*n)
+	p := slices.Grow(dst[len(dst):], 2*len(quote)+len(str)+2*n)
 
 	for len(str) > 0 {
 		i := strings.Index(str, quote)
diff --git a/internal/sanitize/sanitize_fuzz_test.go b/internal/sanitize/sanitize_fuzz_test.go
index a8f2e7791..2f0c41223 100644
--- a/internal/sanitize/sanitize_fuzz_test.go
+++ b/internal/sanitize/sanitize_fuzz_test.go
@@ -1,6 +1,7 @@
 package sanitize_test
 
 import (
+	"strings"
 	"testing"
 
 	"github.com/jackc/pgx/v5/internal/sanitize"