diff --git a/src/makefiles/Makefile.cygwin b/src/makefiles/Makefile.cygwin
index 052ce22ddbf..0a0680c74cc 100644
--- a/src/makefiles/Makefile.cygwin
+++ b/src/makefiles/Makefile.cygwin
@@ -25,6 +25,10 @@ endif
 endif
 endif
 
+ifneq (,$(findstring src/common,$(subdir)))
+override CPPFLAGS+= -DBUILDING_DLL
+endif
+
 ifneq (,$(findstring timezone,$(subdir)))
 override CPPFLAGS+= -DBUILDING_DLL
 endif
diff --git a/src/makefiles/Makefile.win32 b/src/makefiles/Makefile.win32
index dbeff298d84..1aae9e95df1 100644
--- a/src/makefiles/Makefile.win32
+++ b/src/makefiles/Makefile.win32
@@ -23,6 +23,10 @@ endif
 endif
 endif
 
+ifneq (,$(findstring src/common,$(subdir)))
+override CPPFLAGS+= -DBUILDING_DLL
+endif
+
 ifneq (,$(findstring timezone,$(subdir)))
 override CPPFLAGS+= -DBUILDING_DLL
 endif