Index: rijndael.cpp
--- rijndael.cpp.orig
+++ rijndael.cpp
@@ -126,6 +126,12 @@ void Rijndael::Init(bool Encrypt,const byte *key,uint 
     // because "hw.optional.arm.FEAT_AES" was missing in OS X 11, but AES
     // still was supported by Neon.
     AES_Neon=RetCode!=0 || Value!=0;
+  #elif __OpenBSD__
+    const int ISAR0_MIB[] = { CTL_MACHDEP, CPU_ID_AA64ISAR0 };
+    uint64_t ISAR0;
+    size_t Size=sizeof(ISAR0);
+    int RetCode=sysctl(ISAR0_MIB, 2, &ISAR0, &Size, NULL, 0);
+    AES_Neon=RetCode!=-1 && ID_AA64ISAR0_AES(ISAR0)>=ID_AA64ISAR0_AES_BASE;
   #else
     AES_Neon=(getauxval(AT_HWCAP) & HWCAP_AES)!=0;
   #endif
