diff --git a/filter.go b/filter.go
index bb67872..e784600 100644
--- a/filter.go
+++ b/filter.go
@@ -46,7 +46,7 @@ func (ef Filter) Matches(event *Event) bool {
 		return false
 	}
 
-	if ef.IDs != nil && !ContainsPrefixOf(ef.IDs, event.ID) {
+	if ef.IDs != nil && !containsPrefixOf(ef.IDs, event.ID) {
 		return false
 	}
 
@@ -54,7 +54,7 @@ func (ef Filter) Matches(event *Event) bool {
 		return false
 	}
 
-	if ef.Authors != nil && !ContainsPrefixOf(ef.Authors, event.PubKey) {
+	if ef.Authors != nil && !containsPrefixOf(ef.Authors, event.PubKey) {
 		return false
 	}
 
@@ -76,15 +76,15 @@ func (ef Filter) Matches(event *Event) bool {
 }
 
 func FilterEqual(a Filter, b Filter) bool {
-	if !Similar(a.Kinds, b.Kinds) {
+	if !similar(a.Kinds, b.Kinds) {
 		return false
 	}
 
-	if !Similar(a.IDs, b.IDs) {
+	if !similar(a.IDs, b.IDs) {
 		return false
 	}
 
-	if !Similar(a.Authors, b.Authors) {
+	if !similar(a.Authors, b.Authors) {
 		return false
 	}
 
@@ -96,7 +96,7 @@ func FilterEqual(a Filter, b Filter) bool {
 		if bv, ok := b.Tags[f]; !ok {
 			return false
 		} else {
-			if !Similar(av, bv) {
+			if !similar(av, bv) {
 				return false
 			}
 		}
diff --git a/helpers.go b/helpers.go
index 1b94a8a..b8f6fcf 100644
--- a/helpers.go
+++ b/helpers.go
@@ -1,77 +1 @@
 package nostr
-
-import (
-	"strings"
-
-	"golang.org/x/exp/constraints"
-)
-
-func Similar[E constraints.Ordered](as, bs []E) bool {
-	if len(as) != len(bs) {
-		return false
-	}
-
-	for _, a := range as {
-		for _, b := range bs {
-			if b == a {
-				goto next
-			}
-		}
-		// didn't find a B that corresponded to the current A
-		return false
-
-	next:
-		continue
-	}
-
-	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 {
-	dst = append(dst, '"')
-	for i := 0; i < len(s); i++ {
-		c := s[i]
-		switch {
-		case c == '"':
-			// quotation mark
-			dst = append(dst, []byte{'\\', '"'}...)
-		case c == '\\':
-			// reverse solidus
-			dst = append(dst, []byte{'\\', '\\'}...)
-		case c >= 0x20:
-			// default, rest below are control chars
-			dst = append(dst, c)
-		case c == 0x08:
-			dst = append(dst, []byte{'\\', 'b'}...)
-		case c < 0x09:
-			dst = append(dst, []byte{'\\', 'u', '0', '0', '0', '0' + c}...)
-		case c == 0x09:
-			dst = append(dst, []byte{'\\', 't'}...)
-		case c == 0x0a:
-			dst = append(dst, []byte{'\\', 'n'}...)
-		case c == 0x0c:
-			dst = append(dst, []byte{'\\', 'f'}...)
-		case c == 0x0d:
-			dst = append(dst, []byte{'\\', 'r'}...)
-		case c < 0x10:
-			dst = append(dst, []byte{'\\', 'u', '0', '0', '0', 0x57 + c}...)
-		case c < 0x1a:
-			dst = append(dst, []byte{'\\', 'u', '0', '0', '1', 0x20 + c}...)
-		case c < 0x20:
-			dst = append(dst, []byte{'\\', 'u', '0', '0', '1', 0x47 + c}...)
-		}
-	}
-	dst = append(dst, '"')
-	return dst
-}
diff --git a/utils.go b/utils.go
new file mode 100644
index 0000000..d1adfee
--- /dev/null
+++ b/utils.go
@@ -0,0 +1,77 @@
+package nostr
+
+import (
+	"strings"
+
+	"golang.org/x/exp/constraints"
+)
+
+func similar[E constraints.Ordered](as, bs []E) bool {
+	if len(as) != len(bs) {
+		return false
+	}
+
+	for _, a := range as {
+		for _, b := range bs {
+			if b == a {
+				goto next
+			}
+		}
+		// didn't find a B that corresponded to the current A
+		return false
+
+	next:
+		continue
+	}
+
+	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 {
+	dst = append(dst, '"')
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		switch {
+		case c == '"':
+			// quotation mark
+			dst = append(dst, []byte{'\\', '"'}...)
+		case c == '\\':
+			// reverse solidus
+			dst = append(dst, []byte{'\\', '\\'}...)
+		case c >= 0x20:
+			// default, rest below are control chars
+			dst = append(dst, c)
+		case c == 0x08:
+			dst = append(dst, []byte{'\\', 'b'}...)
+		case c < 0x09:
+			dst = append(dst, []byte{'\\', 'u', '0', '0', '0', '0' + c}...)
+		case c == 0x09:
+			dst = append(dst, []byte{'\\', 't'}...)
+		case c == 0x0a:
+			dst = append(dst, []byte{'\\', 'n'}...)
+		case c == 0x0c:
+			dst = append(dst, []byte{'\\', 'f'}...)
+		case c == 0x0d:
+			dst = append(dst, []byte{'\\', 'r'}...)
+		case c < 0x10:
+			dst = append(dst, []byte{'\\', 'u', '0', '0', '0', 0x57 + c}...)
+		case c < 0x1a:
+			dst = append(dst, []byte{'\\', 'u', '0', '0', '1', 0x20 + c}...)
+		case c < 0x20:
+			dst = append(dst, []byte{'\\', 'u', '0', '0', '1', 0x47 + c}...)
+		}
+	}
+	dst = append(dst, '"')
+	return dst
+}