diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index d368e2349b3b..7d49302f9a96 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -1731,7 +1731,7 @@ public:
     if (!CE) return false;
     uint64_t Value = CE->getValue();
     // i64 value with each byte being either 0 or 0xff.
-    for (unsigned i = 0; i < 8; ++i)
+    for (unsigned i = 0; i < 8; ++i, Value >>= 8)
       if ((Value & 0xff) != 0 && (Value & 0xff) != 0xff) return false;
     return true;
   }
diff --git a/llvm/test/MC/ARM/fp-const-errors.s b/llvm/test/MC/ARM/fp-const-errors.s
index 2a68ddbe727e..a91799ba21d2 100644
--- a/llvm/test/MC/ARM/fp-const-errors.s
+++ b/llvm/test/MC/ARM/fp-const-errors.s
@@ -20,3 +20,6 @@ fconsts s1, #1.0
 
 fconstd d2, #1.0
 @ CHECK: error: invalid floating point immediate
+
+vmov.i64 d0, 0x8000000000000000
+@ CHECK: error: invalid operand for instruction