diff --git a/src/mono/CMakeLists.txt b/src/mono/CMakeLists.txt
index 7cf602f7d3c4a7..22cf849b4460f2 100644
--- a/src/mono/CMakeLists.txt
+++ b/src/mono/CMakeLists.txt
@@ -361,6 +361,8 @@ elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "arm64")
   set(HOST_ARM64 1)
 elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "arm")
   set(HOST_ARM 1)
+  # fixme: use separate defines for host/target
+  set(NO_UNALIGNED_ACCESS 1)
 elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "s390x")
   set(HOST_S390X 1)
 elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "wasm")
@@ -413,6 +415,8 @@ elseif(TARGET_ARCH MATCHES "arm")
   add_definitions("-DARM_FPU_VFP=1")
   set(TARGET_SIZEOF_VOID_P 4)
   set(SIZEOF_REGISTER 4)
+  # fixme: use separate defines for host/target
+  set(NO_UNALIGNED_ACCESS 1)
 elseif(TARGET_ARCH STREQUAL "s390x")
   set(TARGET_S390X 1)
   set(MONO_ARCHITECTURE "\"s390x\"")
diff --git a/src/mono/cmake/config.h.in b/src/mono/cmake/config.h.in
index 4fe9f54caf7d10..d49cbd3b9a9d53 100644
--- a/src/mono/cmake/config.h.in
+++ b/src/mono/cmake/config.h.in
@@ -911,6 +911,9 @@
 /* size of target machine integer registers */
 #define SIZEOF_REGISTER @SIZEOF_REGISTER@
 
+/* host or target doesn't allow unaligned memory access */
+#cmakedefine NO_UNALIGNED_ACCESS 1
+
 /* Support for the visibility ("hidden") attribute */
 #cmakedefine HAVE_VISIBILITY_HIDDEN 1