diff --git a/lib/MC/MCExpr.cpp b/lib/MC/MCExpr.cpp
index 5d2c707..f7ed353 100644
--- a/lib/MC/MCExpr.cpp
+++ b/lib/MC/MCExpr.cpp
@@ -338,7 +338,8 @@
   // Absolutize symbol differences between defined symbols when we have a
   // layout object and the target requests it.
 
-  assert(!(Layout && !Asm));
+  assert((!Layout || Asm) &&
+         "Must have an assembler object if layout is given!");
 
   if (Asm && A && B) {
     const MCSymbol &SA = A->getSymbol();