diff --git a/src/runtime/arch_amd64.go b/src/runtime/arch_amd64.go
index db784327..9fcb739e 100644
--- a/src/runtime/arch_amd64.go
+++ b/src/runtime/arch_amd64.go
@@ -5,7 +5,9 @@ const GOARCH = "amd64"
 // The bitness of the CPU (e.g. 8, 32, 64).
 const TargetBits = 64
 
-// Align on word boundary.
+// Align a pointer.
+// Note that some amd64 instructions (like movaps) expect 16-byte aligned
+// memory, thus the result must be 16-byte aligned.
 func align(ptr uintptr) uintptr {
-	return (ptr + 7) &^ 7
+	return (ptr + 15) &^ 15
 }