diff --git a/src/kernel/terrain.c b/src/kernel/terrain.c
index 2f5b677ea..6090f771c 100644
--- a/src/kernel/terrain.c
+++ b/src/kernel/terrain.c
@@ -63,6 +63,19 @@ const char *terraindata[MAXTERRAINS] = {
 
 static terrain_type *registered_terrains;
 
+#ifndef DISABLE_TESTS
+void test_clear_terrains(void)
+{
+  while (registered_terrains) {
+    terrain_type * t = registered_terrains;
+    registered_terrains = t->next;
+    free(t->_name);
+    free(t->production);
+    free(t);
+  }
+}
+#endif
+
 const terrain_type *terrains(void)
 {
   return registered_terrains;
diff --git a/src/kernel/terrain.h b/src/kernel/terrain.h
index 64de714e7..fca223e01 100644
--- a/src/kernel/terrain.h
+++ b/src/kernel/terrain.h
@@ -67,7 +67,7 @@ extern "C" {
     struct terrain_production *production;
     const struct item_type **herbs;     /* zero-terminated array of herbs */
     const char *(*name) (const struct region * r);
-    const struct terrain_type *next;
+    struct terrain_type *next;
   } terrain_type;
 
   extern const terrain_type *terrains(void);
@@ -77,6 +77,10 @@ extern "C" {
 
   extern void init_terrains(void);
 
+#ifndef DISABLE_TESTS
+  void test_clear_terrains(void);
+#endif
+
 #ifdef __cplusplus
 }
 #endif