diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.cpp b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
index c55403920d8fa6..5384e9196896b3 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntime.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -7692,6 +7692,7 @@ class MappableExprsHandler {
                 break;
               }
             }
+            assert(Size && "Failed to determine structure size");
             CombinedInfo.BasePointers.push_back(BP.getPointer());
             CombinedInfo.Pointers.push_back(LB.getPointer());
             CombinedInfo.Sizes.push_back(CGF.Builder.CreateIntCast(