@@ -15,10 +15,12 @@
  */
 
 #import "OFObject.h"
 #import "OFString.h"
 
+OF_ASSUME_NONNULL_BEGIN
+
 /*!
  * @class OFSystemInfo OFSystemInfo.h ObjFW/OFSystemInfo.h
  *
  * @brief A class for querying information about the system.
  */
@@ -80,11 +82,11 @@
  *
  * If the vendor could not be determined, nil is returned instead.
  *
  * @return The vendor of the CPU
  */
-+ (OFString*)CPUVendor;
++ (nullable OFString*)CPUVendor;
 
 /*!
  * @brief Returns whether the CPU supports MMX.
  *
  * @return Whether the CPU supports MMX
@@ -145,5 +147,7 @@
  *
  * @return Whether the CPU supports AVX2
  */
 + (bool)supportsAVX2;
 @end
+
+OF_ASSUME_NONNULL_END