diff --git a/make/windows/makefiles/defs.make b/make/windows/makefiles/defs.make
index a1c88284cc259f636b4c5f86c4adbe6fed904d03..8037a7b40708f4f6386e3757c063a2a8a9509668 100644
--- a/make/windows/makefiles/defs.make
+++ b/make/windows/makefiles/defs.make
@@ -145,7 +145,12 @@ MAKE_ARGS += ENABLE_FULL_DEBUG_SYMBOLS=$(ENABLE_FULL_DEBUG_SYMBOLS)
 ifeq ($(ENABLE_FULL_DEBUG_SYMBOLS),1)
   # Disable ZIP_DEBUGINFO_FILES by default because various tests are
   # failing in nightly when the debug info files are ZIP'ed.
-  ZIP_DEBUGINFO_FILES ?= 0
+  #ZIP_DEBUGINFO_FILES ?= 0
+  # The above conditional setting logic is unreliable on Windows for
+  # unknown reasons. We force ZIP_DEBUGINFO_FILES to be disabled on
+  # Windows until we figure out why the various tests are failing
+  # AND why the conditional setting logic is unreliable.
+  ZIP_DEBUGINFO_FILES=0
 else
   ZIP_DEBUGINFO_FILES=0
 endif