diff --git a/libs/hwui/jni/FontFamily.cpp b/libs/hwui/jni/FontFamily.cpp
index ce5ac38..f632d09 100644
--- a/libs/hwui/jni/FontFamily.cpp
+++ b/libs/hwui/jni/FontFamily.cpp
@@ -44,6 +44,7 @@
 
 namespace android {
 
+namespace {
 struct NativeFamilyBuilder {
     NativeFamilyBuilder(uint32_t langId, int variant)
         : langId(langId), variant(static_cast<minikin::FamilyVariant>(variant)) {}
@@ -52,6 +53,7 @@
     std::vector<std::shared_ptr<minikin::Font>> fonts;
     std::vector<minikin::FontVariation> axes;
 };
+}  // namespace
 
 static inline NativeFamilyBuilder* toNativeBuilder(jlong ptr) {
     return reinterpret_cast<NativeFamilyBuilder*>(ptr);
diff --git a/libs/hwui/jni/fonts/FontFamily.cpp b/libs/hwui/jni/fonts/FontFamily.cpp
index b682135..ac1c05e 100644
--- a/libs/hwui/jni/fonts/FontFamily.cpp
+++ b/libs/hwui/jni/fonts/FontFamily.cpp
@@ -29,9 +29,11 @@
 
 namespace android {
 
+namespace {
 struct NativeFamilyBuilder {
     std::vector<std::shared_ptr<minikin::Font>> fonts;
 };
+}  // namespace
 
 static inline NativeFamilyBuilder* toBuilder(jlong ptr) {
     return reinterpret_cast<NativeFamilyBuilder*>(ptr);