diff --git a/src/Makefile.shlib b/src/Makefile.shlib
index 86db52fe5e..924d21f443 100644
--- a/src/Makefile.shlib
+++ b/src/Makefile.shlib
@@ -338,7 +338,16 @@ endif
 else # PORTNAME == aix
 
 # AIX case
-$(shlib) $(stlib): $(OBJS) | $(SHLIB_PREREQS)
+
+# There is no correct way to write a rule that generates two files.
+# Rules with two targets don't have that meaning, they are merely
+# shorthand for two otherwise separate rules.  To be safe for parallel
+# make, we must chain the dependencies like this.  The semicolon is
+# important, otherwise make will choose some built-in rule.
+
+$(stlib): $(shlib) ;
+
+$(shlib): $(OBJS) | $(SHLIB_PREREQS)
 	rm -f $(stlib)
 	$(LINK.static) $(stlib) $^
 	$(RANLIB) $(stlib)