diff --git a/CMakeLists.txt b/CMakeLists.txt
index e0aa59b0..4729e5b5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -319,6 +319,17 @@ if(MI_WIN_USE_FLS)
   list(APPEND mi_defines MI_WIN_USE_FLS=1)
 endif()
 
+
+ # Check /proc/cpuinfo for an SV39 MMU and define a constant if one is
+ # found. We will want to skip the aligned hinting in that case. Issue #939, #949
+ if (EXISTS /proc/cpuinfo)
+   file(STRINGS /proc/cpuinfo mi_sv39_mmu REGEX "^mmu[ \t]+:[ \t]+sv39$")
+   if (mi_sv39_mmu)
+     MESSAGE( STATUS "Disable aligned hints (SV39 MMU detected)" )
+     list(APPEND mi_defines MI_NO_ALIGNED_HINT=1)
+   endif()
+ endif()
+
 # On Haiku use `-DCMAKE_INSTALL_PREFIX` instead, issue #788
 # if(CMAKE_SYSTEM_NAME MATCHES "Haiku")
 #   SET(CMAKE_INSTALL_LIBDIR ~/config/non-packaged/lib)
diff --git a/src/os.c b/src/os.c
index 4babd8da..4b9d6125 100644
--- a/src/os.c
+++ b/src/os.c
@@ -92,8 +92,9 @@ static void* mi_align_down_ptr(void* p, size_t alignment) {
 -------------------------------------------------------------- */
 
 // On 64-bit systems, we can do efficient aligned allocation by using
-// the 2TiB to 30TiB area to allocate those.
-#if (MI_INTPTR_SIZE >= 8)
+// the 2TiB to 30TiB area to allocate those. We assume we have
+// at least 48 bits of virtual address space on 64-bit systems (but see issue #939)
+#if (MI_INTPTR_SIZE >= 8) && !defined(MI_NO_ALIGNED_HINT)
 static mi_decl_cache_align _Atomic(uintptr_t)aligned_base;
 
 // Return a MI_SEGMENT_SIZE aligned address that is probably available.
@@ -239,7 +240,7 @@ static void* mi_os_prim_alloc_aligned(size_t size, size_t alignment, bool commit
   if (!(alignment >= _mi_os_page_size() && ((alignment & (alignment - 1)) == 0))) return NULL;
   size = _mi_align_up(size, _mi_os_page_size());
 
-  // try first with a hint (this will be aligned directly on Win 10+ or BSD)
+  // try first with a requested alignment hint (this will usually be aligned directly on Win 10+ or BSD)
   void* p = mi_os_prim_alloc(size, alignment, commit, allow_large, is_large, is_zero, stats);
   if (p == NULL) return NULL;