diff --git a/mozilla/content/canvas/src/Makefile.in b/mozilla/content/canvas/src/Makefile.in
index ee2a83aacc4..d39673c69ea 100644
--- a/mozilla/content/canvas/src/Makefile.in
+++ b/mozilla/content/canvas/src/Makefile.in
@@ -75,7 +75,12 @@ REQUIRES	= \
 		plugin \
 		$(NULL)
 
-CPPSRCS		= \
+# XXX some platforms can't handle building
+# an empty .a/lib.  Remove this dummy.cpp
+# whenever w have a rendering context
+# that doesn't depend on any non-default
+# libraries.
+CPPSRCS		= dummy.cpp \
 		$(NULL)
 
 ifdef MOZ_ENABLE_CAIRO
diff --git a/mozilla/content/canvas/src/dummy.cpp b/mozilla/content/canvas/src/dummy.cpp
new file mode 100644
index 00000000000..7e06bf6b6db
--- /dev/null
+++ b/mozilla/content/canvas/src/dummy.cpp
@@ -0,0 +1,4 @@
+/*
+ * This file only exists because some platforms can't handle building an empty .a
+ * file, or .lib, or whatever (e.g. OS X, possibly Win32).
+ */