Use versioned library names on Darwin too
diff --git a/Makefile b/Makefile
index 84556ac..cbdd1f1 100644
--- a/Makefile
+++ b/Makefile
@@ -186,6 +186,7 @@
 # OSX?
 ifeq ($(UNAME_S),Darwin)
 EXT = dylib
+VERSION_EXT = $(API_MAJOR).$(EXT)
 AR_EXT = a
 ifneq ($(USE_SYS_DYN_MEM),yes)
 # remove string check because OSX kernel complains about missing symbols