diff --git a/Makefile.common b/Makefile.common
index 46d18c61892..aef05750ace 100644
--- a/Makefile.common
+++ b/Makefile.common
@@ -29,6 +29,11 @@
 #ENABLE_PURIFY    = 1
 #ENABLE_OPTIMIZED = 1
 
+ifdef SHARED_LIBRARY
+# if SHARED_LIBRARY is specified, the default is to build the dynamic lib
+dynamic ::
+endif
+
 # Default Rule:  Make sure it's also a :: rule
 all ::
 
diff --git a/Makefile.rules b/Makefile.rules
index 46d18c61892..aef05750ace 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -29,6 +29,11 @@
 #ENABLE_PURIFY    = 1
 #ENABLE_OPTIMIZED = 1
 
+ifdef SHARED_LIBRARY
+# if SHARED_LIBRARY is specified, the default is to build the dynamic lib
+dynamic ::
+endif
+
 # Default Rule:  Make sure it's also a :: rule
 all ::