diff --git a/src/kits/storage/mime/AssociatedTypes.cpp b/src/kits/storage/mime/AssociatedTypes.cpp
index f207ddaa49..d3e208b7b4 100644
--- a/src/kits/storage/mime/AssociatedTypes.cpp
+++ b/src/kits/storage/mime/AssociatedTypes.cpp
@@ -375,9 +375,8 @@ AssociatedTypes::BuildAssociatedTypesTable()
 								if (subEntry.GetName(subtype) == B_OK) {
 									BPrivate::Storage::to_lower(subtype);
 
-									char fulltype[B_PATH_NAME_LENGTH];
-									snprintf(fulltype, B_PATH_NAME_LENGTH, "%s/%s",
-										supertype, subtype);
+									BString fulltype;
+									fulltype.SetToFormat("%s/%s", supertype, subtype);
 
 									// Process the subtype
 									ProcessType(fulltype);
diff --git a/src/kits/storage/mime/SnifferRules.cpp b/src/kits/storage/mime/SnifferRules.cpp
index f9211fb674..de9ade3122 100644
--- a/src/kits/storage/mime/SnifferRules.cpp
+++ b/src/kits/storage/mime/SnifferRules.cpp
@@ -373,9 +373,8 @@ SnifferRules::BuildRuleList()
 								if (subEntry.GetName(subtype) == B_OK) {
 									BPrivate::Storage::to_lower(subtype);
 
-									char fulltype[B_PATH_NAME_LENGTH];
-									snprintf(fulltype, B_PATH_NAME_LENGTH, "%s/%s",
-										supertype, subtype);
+									BString fulltype;
+									fulltype.SetToFormat("%s/%s", supertype, subtype);
 
 									// Process the subtype
 									ProcessType(fulltype, &bytesNeeded);