diff --git a/build/autoconf/compiler-opts.m4 b/build/autoconf/compiler-opts.m4
index 82d0b43fc6..77c2e85b5e 100644
--- a/build/autoconf/compiler-opts.m4
+++ b/build/autoconf/compiler-opts.m4
@@ -176,8 +176,13 @@ if test "$GNU_CC"; then
         CFLAGS="$CFLAGS -ffunction-sections -fdata-sections"
         CXXFLAGS="$CXXFLAGS -ffunction-sections -fdata-sections"
     fi
-    CFLAGS="$CFLAGS -fno-math-errno -msse2 -mfpmath=sse"
-    CXXFLAGS="$CXXFLAGS -fno-exceptions -fno-math-errno -msse2 -mfpmath=sse"
+    CFLAGS="$CFLAGS -fno-math-errno"
+    CXXFLAGS="$CXXFLAGS -fno-exceptions -fno-math-errno"
+
+    if test "$CPU_ARCH" = "x86" -o "$CPU_ARCH" = "x86_64"; then
+      CFLAGS="$CFLAGS -msse2 -mfpmath=sse"
+      CXXFLAGS="$CXXFLAGS -msse2 -mfpmath=sse"
+    fi
 
     if test -z "$CLANG_CC"; then
         case "$CC_VERSION" in
diff --git a/mozglue/build/WindowsDllBlocklist.cpp b/mozglue/build/WindowsDllBlocklist.cpp
index ccfcf9dd10..859114321c 100644
--- a/mozglue/build/WindowsDllBlocklist.cpp
+++ b/mozglue/build/WindowsDllBlocklist.cpp
@@ -231,6 +231,9 @@ static DllBlockInfo sWindowsDllBlocklist[] = {
   // Comodo IS old versions, startup crash on 64-bit, bug 1140397
   { "guard64.dll", MAKE_VERSION(6, 3, 0, 0) },
 
+  // 360 Safeguard/360 Total Security causes a11y crashes, bug 1536227.
+  { "safemon64.dll", ALL_VERSIONS },
+
   { nullptr, 0 }
 };