diff --git a/include/globalvar.h b/include/globalvar.h
index 6e10956..e77209b 100644
--- a/include/globalvar.h
+++ b/include/globalvar.h
@@ -60,7 +60,7 @@
 }
 
 static inline int globalvar_add_simple_enum(const char *name,
-		int *value, const char **names, int max)
+		int *value, const char * const *names, int max)
 {
 	struct param_d *p;
 
@@ -117,7 +117,7 @@
 }
 
 static inline int globalvar_add_simple_enum(const char *name,
-		int *value, const char **names, int max)
+		int *value, const char * const *names, int max)
 {
 	return 0;
 }
diff --git a/include/param.h b/include/param.h
index 3a851fc..3fb4740 100644
--- a/include/param.h
+++ b/include/param.h
@@ -50,7 +50,7 @@
 struct param_d *dev_add_param_enum(struct device_d *dev, const char *name,
 		int (*set)(struct param_d *p, void *priv),
 		int (*get)(struct param_d *p, void *priv),
-		int *value, const char **names, int max, void *priv);
+		int *value, const char * const *names, int max, void *priv);
 
 struct param_d *dev_add_param_int_ro(struct device_d *dev, const char *name,
 		int value, const char *format);
@@ -120,7 +120,7 @@
 static inline struct param_d *dev_add_param_enum(struct device_d *dev, const char *name,
 		int (*set)(struct param_d *p, void *priv),
 		int (*get)(struct param_d *p, void *priv),
-		int *value, const char **names, int max, void *priv)
+		int *value, const char * const *names, int max, void *priv)
 
 {
 	return ERR_PTR(-ENOSYS);
diff --git a/lib/parameter.c b/lib/parameter.c
index b238859..fd05b49 100644
--- a/lib/parameter.c
+++ b/lib/parameter.c
@@ -389,8 +389,8 @@
 
 struct param_enum {
 	struct param_d param;
-	int *value;
-	const char **names;
+	unsigned int *value;
+	const char * const *names;
 	int num_names;
 	int (*set)(struct param_d *p, void *priv);
 	int (*get)(struct param_d *p, void *priv);
@@ -441,7 +441,11 @@
 	}
 
 	free(p->value);
-	p->value = strdup(pe->names[*pe->value]);
+
+	if (*pe->value >= pe->num_names)
+		p->value = asprintf("invalid:%d", *pe->value);
+	else
+		p->value = strdup(pe->names[*pe->value]);
 
 	return p->value;
 }
@@ -467,7 +471,7 @@
 struct param_d *dev_add_param_enum(struct device_d *dev, const char *name,
 		int (*set)(struct param_d *p, void *priv),
 		int (*get)(struct param_d *p, void *priv),
-		int *value, const char **names, int num_names, void *priv)
+		int *value, const char * const *names, int num_names, void *priv)
 {
 	struct param_enum *pe;
 	struct param_d *p;