diff --git a/indra/llmath/llcalcparser.h b/indra/llmath/llcalcparser.h
index bd9c8c2519..e6298b7e74 100644
--- a/indra/llmath/llcalcparser.h
+++ b/indra/llmath/llcalcparser.h
@@ -27,6 +27,8 @@
 #ifndef LL_CALCPARSER_H
 #define LL_CALCPARSER_H
 
+#define BOOST_SPIRIT_SINGLE_GRAMMAR_INSTANCE
+
 #include <boost/spirit/include/classic_attribute.hpp>
 #include <boost/spirit/include/classic_core.hpp>
 #include <boost/spirit/include/classic_error_handling.hpp>
diff --git a/indra/newview/fslslpreproc.cpp b/indra/newview/fslslpreproc.cpp
index e46a003389..6224883460 100644
--- a/indra/newview/fslslpreproc.cpp
+++ b/indra/newview/fslslpreproc.cpp
@@ -110,6 +110,7 @@ std::map<std::string,LLUUID> FSLSLPreprocessor::cached_assetids;
 #ifdef LL_WINDOWS
 #pragma warning (disable : 4702) // warning C4702: unreachable code
 #endif
+#define BOOST_SPIRIT_SINGLE_GRAMMAR_INSTANCE
 
 #include <boost/assert.hpp>
 #include <boost/wave.hpp>