diff --git a/filter.go b/filter.go
index c84a401..9ff2c06 100644
--- a/filter.go
+++ b/filter.go
@@ -45,7 +45,7 @@ func (ef Filter) Matches(event *Event) bool {
 		return false
 	}
 
-	if ef.IDs != nil && !containsPrefixOf(ef.IDs, event.ID) {
+	if ef.IDs != nil && !slices.Contains(ef.IDs, event.ID) {
 		return false
 	}
 
@@ -53,7 +53,7 @@ func (ef Filter) Matches(event *Event) bool {
 		return false
 	}
 
-	if ef.Authors != nil && !containsPrefixOf(ef.Authors, event.PubKey) {
+	if ef.Authors != nil && !slices.Contains(ef.Authors, event.PubKey) {
 		return false
 	}
 
@@ -63,11 +63,11 @@ func (ef Filter) Matches(event *Event) bool {
 		}
 	}
 
-	if ef.Since != nil && event.CreatedAt < *ef.Since {
+	if ef.Since != nil && event.CreatedAt <= *ef.Since {
 		return false
 	}
 
-	if ef.Until != nil && event.CreatedAt > *ef.Until {
+	if ef.Until != nil && event.CreatedAt >= *ef.Until {
 		return false
 	}
 
diff --git a/utils.go b/utils.go
index 7b626a2..cdeeae5 100644
--- a/utils.go
+++ b/utils.go
@@ -28,15 +28,6 @@ func similar[E constraints.Ordered](as, bs []E) bool {
 	return true
 }
 
-func containsPrefixOf(haystack []string, needle string) bool {
-	for _, hay := range haystack {
-		if strings.HasPrefix(needle, hay) {
-			return true
-		}
-	}
-	return false
-}
-
 // Escaping strings for JSON encoding according to RFC8259.
 // Also encloses result in quotation marks "".
 func escapeString(dst []byte, s string) []byte {