--- a/js/src/jit/x64/CodeGenerator-x64.cpp
+++ b/js/src/jit/x64/CodeGenerator-x64.cpp
@@ -594,21 +594,21 @@ CodeGeneratorX64::loadSimd(Scalar::Type 
           // See comment above, which also applies to movq.
           case 2: masm.vmovq(srcAddr, out); break;
           case 4: masm.loadUnalignedSimd128Int(srcAddr, out); break;
           default: MOZ_CRASH("unexpected size for partial load");
         }
         break;
       }
       case Scalar::Int8x16:
-        MOZ_ASSERT(numElems = 16, "unexpected partial load");
+        MOZ_ASSERT(numElems == 16, "unexpected partial load");
         masm.loadUnalignedSimd128Int(srcAddr, out);
         break;
       case Scalar::Int16x8:
-        MOZ_ASSERT(numElems = 8, "unexpected partial load");
+        MOZ_ASSERT(numElems == 8, "unexpected partial load");
         masm.loadUnalignedSimd128Int(srcAddr, out);
         break;
       case Scalar::Int8:
       case Scalar::Uint8:
       case Scalar::Int16:
       case Scalar::Uint16:
       case Scalar::Int32:
       case Scalar::Uint32: