diff --git a/flect_test.go b/flect_test.go
index 4ab6251..4dd7054 100644
--- a/flect_test.go
+++ b/flect_test.go
@@ -333,6 +333,7 @@ var singlePluralAssertions = []dict{
 	{"ID", "IDs", true, true},
 	{"IDS", "IDSes", true, true},
 	// id to ids (ID), ids to idses (IDS) is not supported
+	{"ids", "ids", true, true},
 	{"api", "apis", true, true},
 	{"API", "APIs", true, true},
 	{"html", "htmls", true, true},
@@ -343,6 +344,9 @@ var singlePluralAssertions = []dict{
 	{"SSH", "SSHs", true, true},
 	{"eia", "eias", true, true}, // ia
 	{"EIA", "EIAs", true, true},
+	{"https", "https", true, true},
+	{"HTTPS", "HTTPSes", true, true},
+	{"dns", "dns", true, true},
 	{"DNS", "DNSes", true, true},
 }
 
diff --git a/pluralize.go b/pluralize.go
index d0ac77d..0eb664a 100644
--- a/pluralize.go
+++ b/pluralize.go
@@ -59,7 +59,8 @@ func (i Ident) Pluralize() Ident {
 	}
 
 	for _, r := range pluralRules {
-		if strings.HasSuffix(s, r.suffix) {
+		// Acronym parts are normalized to uppercase, so only replace an exact suffix.
+		if strings.HasSuffix(s, r.suffix) && strings.HasSuffix(i.Original, s) {
 			return i.ReplaceSuffix(s, r.fn(s))
 		}
 	}
diff --git a/singularize.go b/singularize.go
index d00cf4f..2f42450 100644
--- a/singularize.go
+++ b/singularize.go
@@ -56,7 +56,8 @@ func (i Ident) Singularize() Ident {
 	}
 
 	for _, r := range singularRules {
-		if strings.HasSuffix(s, r.suffix) {
+		// Acronym parts are normalized to uppercase, so only replace an exact suffix.
+		if strings.HasSuffix(s, r.suffix) && strings.HasSuffix(i.Original, s) {
 			return i.ReplaceSuffix(s, r.fn(s))
 		}
 	}