diff --git a/intern/cycles/util/util_optimization.h b/intern/cycles/util/util_optimization.h
index 0382c0811dd..3c5785c4807 100644
--- a/intern/cycles/util/util_optimization.h
+++ b/intern/cycles/util/util_optimization.h
@@ -25,6 +25,9 @@
 
 #if defined(i386) || defined(_M_IX86)
 
+/* We require minimum SSE2 support on x86, so auto enable. */
+#  define __KERNEL_SSE2__
+
 #  ifdef WITH_KERNEL_SSE2
 #    define WITH_CYCLES_OPTIMIZED_KERNEL_SSE2
 #  endif