diff --git a/mem/mem.c b/mem/mem.c
index 83facfccfe5..38a889ae914 100644
--- a/mem/mem.c
+++ b/mem/mem.c
@@ -60,6 +60,7 @@ unsigned long (*gen_pkg_get_frags)(void *blk);
 
 int set_pkg_mm(const char *mm_name)
 {
+#ifdef PKG_MALLOC
 #ifdef INLINE_ALLOC
 	LM_NOTICE("this is an inlined allocator build (see opensips -V), "
 	          "cannot set a custom pkg allocator (%s)\n", mm_name);
@@ -70,6 +71,10 @@ int set_pkg_mm(const char *mm_name)
 		return -1;
 
 	return 0;
+#else
+	LM_ERR("cannot change pkg allocator when system malloc is used!\n");
+	return -1;
+#endif
 }
 
 int init_pkg_mallocs(void)
diff --git a/mem/mem.h b/mem/mem.h
index fc77e3b67e6..0d30fe15a76 100644
--- a/mem/mem.h
+++ b/mem/mem.h
@@ -30,11 +30,12 @@
 #include "../dprint.h"
 
 #include "mem_funcs.h"
-#ifdef PKG_MALLOC
-#include "common.h"
 
 int set_pkg_mm(const char *mm_name);
 
+#ifdef PKG_MALLOC
+#include "common.h"
+
 extern char *mem_pool;
 extern enum osips_mm mem_allocator_pkg;