diff --git a/indra/newview/CMakeLists.txt b/indra/newview/CMakeLists.txt
index 766dc5226ca7256be11059566e8dee5634bb77da..c18b2c9a959e5964bd6a9006b7355f82a8bc5cb8 100644
--- a/indra/newview/CMakeLists.txt
+++ b/indra/newview/CMakeLists.txt
@@ -1381,8 +1381,12 @@ if (DARWIN)
     PROPERTIES
     COMPILE_DEFINITIONS "${VIEWER_CHANNEL_VERSION_DEFINES}"
     # BugsplatMac is a module, imported with @import. That language feature
-    # demands these switches.
-    COMPILE_FLAGS "-fmodules -fcxx-modules"
+    # demands these -f switches.
+    # Xcode 10.2 requires that Objective-C++ headers declare nullability of
+    # pointer variables. As of 2019-06-26, the BugsplatMac version we're using
+    # does not yet do so in its own header files. This -W flag prevents fatal
+    # warnings.
+    COMPILE_FLAGS "-fmodules -fcxx-modules -Wno-nullability-completeness"
     )
 
   find_library(AGL_LIBRARY AGL)