diff --git a/src/interfaces/ecpg/compatlib/Makefile b/src/interfaces/ecpg/compatlib/Makefile
index 3545d2b0323..ca489d32b94 100644
--- a/src/interfaces/ecpg/compatlib/Makefile
+++ b/src/interfaces/ecpg/compatlib/Makefile
@@ -18,7 +18,7 @@ SO_MAJOR_VERSION= 3
 SO_MINOR_VERSION= 5
 
 override CPPFLAGS := -I../include -I$(top_srcdir)/src/interfaces/ecpg/include \
-	-I$(libpq_srcdir) -I$(top_srcdir)/src/include/utils $(CPPFLAGS)
+	-I$(libpq_srcdir) -I$(top_srcdir)/src/include/utils -DFRONTEND $(CPPFLAGS)
 override CFLAGS += $(PTHREAD_CFLAGS)
 
 SHLIB_LINK = -L../ecpglib -lecpg -L../pgtypeslib -lpgtypes $(libpq) \
diff --git a/src/interfaces/ecpg/pgtypeslib/Makefile b/src/interfaces/ecpg/pgtypeslib/Makefile
index 09b5df30999..340bef398bd 100644
--- a/src/interfaces/ecpg/pgtypeslib/Makefile
+++ b/src/interfaces/ecpg/pgtypeslib/Makefile
@@ -18,7 +18,7 @@ SO_MAJOR_VERSION= 3
 SO_MINOR_VERSION= 4
 
 override CPPFLAGS := -I../include -I$(top_srcdir)/src/interfaces/ecpg/include \
-	-I$(top_srcdir)/src/include/utils -I$(libpq_srcdir) $(CPPFLAGS)
+	-I$(top_srcdir)/src/include/utils -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
 override CFLAGS += $(PTHREAD_CFLAGS)
 
 # Need to recompile any libpgport object files
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 94c7fee8556..3782ec53a23 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -306,6 +306,7 @@ sub mkvcbuild
 	my $libecpgcompat = $solution->AddProject(
 		'libecpg_compat', 'dll',
 		'interfaces',     'src\interfaces\ecpg\compatlib');
+	$libecpgcompat->AddDefine('FRONTEND');
 	$libecpgcompat->AddIncludeDir('src\interfaces\ecpg\include');
 	$libecpgcompat->AddIncludeDir('src\interfaces\libpq');
 	$libecpgcompat->UseDef('src\interfaces\ecpg\compatlib\compatlib.def');