diff --git a/impeller/geometry/matrix.h b/impeller/geometry/matrix.h
index 70a58482b863b..6b7e4453645e3 100644
--- a/impeller/geometry/matrix.h
+++ b/impeller/geometry/matrix.h
@@ -39,7 +39,7 @@ struct Matrix {
   };
 
   //----------------------------------------------------------------------------
-  /// Construts a default identity matrix.
+  /// Constructs a default identity matrix.
   ///
   constexpr Matrix()
       // clang-format off
diff --git a/impeller/renderer/allocator.cc b/impeller/renderer/allocator.cc
index 5969d220c21a7..74d9e1d4bc812 100644
--- a/impeller/renderer/allocator.cc
+++ b/impeller/renderer/allocator.cc
@@ -15,13 +15,13 @@ bool Allocator::RequiresExplicitHostSynchronization(StorageMode mode) {
     return false;
   }
 
-#if OS_IOS
+#if FML_OS_IOS
   // StorageMode::kHostVisible is MTLStorageModeShared already.
   return false;
-#else   // OS_IOS
+#else   // FML_OS_IOS
   // StorageMode::kHostVisible is MTLResourceStorageModeManaged.
   return true;
-#endif  // OS_IOS
+#endif  // FML_OS_IOS
 }
 
 }  // namespace impeller
diff --git a/impeller/renderer/backend/metal/allocator_mtl.mm b/impeller/renderer/backend/metal/allocator_mtl.mm
index 4cbe7ac143646..20ceb1e2c7910 100644
--- a/impeller/renderer/backend/metal/allocator_mtl.mm
+++ b/impeller/renderer/backend/metal/allocator_mtl.mm
@@ -32,7 +32,7 @@
 static MTLResourceOptions ToMTLResourceOptions(StorageMode type) {
   switch (type) {
     case StorageMode::kHostVisible:
-#if OS_IOS
+#if FML_OS_IOS
       return MTLResourceStorageModeShared;
 #else
       return MTLResourceStorageModeManaged;
@@ -40,7 +40,7 @@ static MTLResourceOptions ToMTLResourceOptions(StorageMode type) {
     case StorageMode::kDevicePrivate:
       return MTLResourceStorageModePrivate;
     case StorageMode::kDeviceTransient:
-#if OS_IOS
+#if FML_OS_IOS
       if (@available(iOS 10.0, *)) {
         return MTLResourceStorageModeMemoryless;
       } else {
@@ -57,7 +57,7 @@ static MTLResourceOptions ToMTLResourceOptions(StorageMode type) {
 static MTLStorageMode ToMTLStorageMode(StorageMode mode) {
   switch (mode) {
     case StorageMode::kHostVisible:
-#if OS_IOS
+#if FML_OS_IOS
       return MTLStorageModeShared;
 #else
       return MTLStorageModeManaged;
@@ -65,7 +65,7 @@ static MTLStorageMode ToMTLStorageMode(StorageMode mode) {
     case StorageMode::kDevicePrivate:
       return MTLStorageModePrivate;
     case StorageMode::kDeviceTransient:
-#if OS_IOS
+#if FML_OS_IOS
       if (@available(iOS 10.0, *)) {
         return MTLStorageModeMemoryless;
       } else {
diff --git a/impeller/renderer/backend/metal/device_buffer_mtl.mm b/impeller/renderer/backend/metal/device_buffer_mtl.mm
index cb6415f89b13d..3f47629aa27f4 100644
--- a/impeller/renderer/backend/metal/device_buffer_mtl.mm
+++ b/impeller/renderer/backend/metal/device_buffer_mtl.mm
@@ -79,7 +79,7 @@
 // Making this call is never necessary on iOS because there is no
 // MTLResourceStorageModeManaged mode. Only the MTLStorageModeShared mode is
 // available.
-#if !OS_IOS
+#if !FML_OS_IOS
   if (Allocator::RequiresExplicitHostSynchronization(mode_)) {
     [buffer_ didModifyRange:NSMakeRange(offset, source_range.length)];
   }
diff --git a/impeller/renderer/platform.h b/impeller/renderer/platform.h
index 464d47451ac33..1ca8133c328c5 100644
--- a/impeller/renderer/platform.h
+++ b/impeller/renderer/platform.h
@@ -12,7 +12,7 @@
 namespace impeller {
 
 constexpr size_t DefaultUniformAlignment() {
-#if OS_IOS
+#if FML_OS_IOS
   return 16u;
 #elif FML_OS_MACOSX
   return 256u;