diff --git a/libstdc++-v3/src/c++11/compatibility-ldbl-facets-aliases.h b/libstdc++-v3/src/c++11/compatibility-ldbl-facets-aliases.h
index 70c9342d88a..faf8221b273 100644
--- a/libstdc++-v3/src/c++11/compatibility-ldbl-facets-aliases.h
+++ b/libstdc++-v3/src/c++11/compatibility-ldbl-facets-aliases.h
@@ -23,11 +23,11 @@
 // <http://www.gnu.org/licenses/>.
 
 #ifndef C
-#define "This file should not be compiled directly, only included"
+# error "This file should not be compiled directly, only included"
 #endif
 
 #ifndef _GLIBCXX_LONG_DOUBLE_COMPAT
-#define "This file should only be used for _GLIBCXX_LONG_DOUBLE_COMPAT builds"
+# error "This file should only be used for _GLIBCXX_LONG_DOUBLE_COMPAT builds"
 #endif
 
 // XXX GLIBCXX_ABI Deprecated
diff --git a/libstdc++-v3/src/c++11/locale-inst-monetary.h b/libstdc++-v3/src/c++11/locale-inst-monetary.h
index d8fecf26596..954de1f52cf 100644
--- a/libstdc++-v3/src/c++11/locale-inst-monetary.h
+++ b/libstdc++-v3/src/c++11/locale-inst-monetary.h
@@ -23,7 +23,7 @@
 // <http://www.gnu.org/licenses/>.
 
 #ifndef C
-#define "This file should not be compiled directly, only included"
+# error "This file should not be compiled directly, only included"
 #endif
 
 #include "facet_inst_macros.h"
diff --git a/libstdc++-v3/src/c++11/locale-inst-numeric.h b/libstdc++-v3/src/c++11/locale-inst-numeric.h
index c77ee9e8d38..b917fe5802e 100644
--- a/libstdc++-v3/src/c++11/locale-inst-numeric.h
+++ b/libstdc++-v3/src/c++11/locale-inst-numeric.h
@@ -23,7 +23,7 @@
 // <http://www.gnu.org/licenses/>.
 
 #ifndef C
-#define "This file should not be compiled directly, only included"
+# error "This file should not be compiled directly, only included"
 #endif
 
 #include "facet_inst_macros.h"