diff --git a/libraries/AP_Terrain/AP_Terrain.h b/libraries/AP_Terrain/AP_Terrain.h
index 7dfd2653d8..1bbdaeb05b 100644
--- a/libraries/AP_Terrain/AP_Terrain.h
+++ b/libraries/AP_Terrain/AP_Terrain.h
@@ -108,6 +108,7 @@ public:
 
     bool pre_arm_checks(char *failure_msg, uint8_t failure_msg_len) const;
 
+#if HAL_GCS_ENABLED
     // send any pending terrain request message
     bool send_cache_request(mavlink_channel_t chan);
     void send_request(mavlink_channel_t chan);
@@ -117,6 +118,7 @@ public:
     void handle_data(mavlink_channel_t chan, const mavlink_message_t &msg);
     void handle_terrain_check(mavlink_channel_t chan, const mavlink_message_t &msg);
     void handle_terrain_data(const mavlink_message_t &msg);
+#endif
 
     /*
       find the terrain height in meters above sea level for a location
@@ -318,11 +320,13 @@ private:
     */
     bool check_bitmap(const struct grid_block &grid, uint8_t idx_x, uint8_t idx_y);
 
+#if HAL_GCS_ENABLED
     /*
       request any missing 4x4 grids from a block
     */
     bool request_missing(mavlink_channel_t chan, struct grid_cache &gcache);
     bool request_missing(mavlink_channel_t chan, const struct grid_info &info);
+#endif
 
     /*
       look for blocks that need to be read/written to disk
@@ -394,8 +398,10 @@ private:
     volatile enum DiskIoState disk_io_state;
     union grid_io_block disk_block;
 
+#if HAL_GCS_ENABLED
     // last time we asked for more grids
     uint32_t last_request_time_ms[MAVLINK_COMM_NUM_BUFFERS];
+#endif
 
     static const uint64_t bitmap_mask = (((uint64_t)1U)<<(TERRAIN_GRID_BLOCK_MUL_X*TERRAIN_GRID_BLOCK_MUL_Y)) - 1;
 
diff --git a/libraries/AP_Terrain/TerrainGCS.cpp b/libraries/AP_Terrain/TerrainGCS.cpp
index 30a2067c29..e65b874041 100644
--- a/libraries/AP_Terrain/TerrainGCS.cpp
+++ b/libraries/AP_Terrain/TerrainGCS.cpp
@@ -32,14 +32,12 @@
 
 extern const AP_HAL::HAL& hal;
 
+#if HAL_GCS_ENABLED
 /*
   request any missing 4x4 grids from a block, given a grid_cache
  */
 bool AP_Terrain::request_missing(mavlink_channel_t chan, struct grid_cache &gcache)
 {
-#if !HAL_GCS_ENABLED
-    return false;
-#else
     struct grid_block &grid = gcache.grid;
 
     if (options.get() & uint16_t(Options::DisableDownload)) {
@@ -75,7 +73,6 @@ bool AP_Terrain::request_missing(mavlink_channel_t chan, struct grid_cache &gcac
     last_request_time_ms[chan] = AP_HAL::millis();
 
     return true;
-#endif
 }
 
 /*
@@ -157,6 +154,7 @@ void AP_Terrain::send_request(mavlink_channel_t chan)
         return;
     }
 }
+#endif  // HAL_GCS_ENABLED
 
 /*
   count bits in a uint64_t
@@ -196,7 +194,8 @@ void AP_Terrain::get_statistics(uint16_t &pending, uint16_t &loaded) const
     }
 }
 
-/* 
+#if HAL_GCS_ENABLED
+/*
    handle terrain messages from GCS
  */
 void AP_Terrain::handle_data(mavlink_channel_t chan, const mavlink_message_t &msg)
@@ -312,6 +311,7 @@ void AP_Terrain::handle_terrain_data(const mavlink_message_t &msg)
     // see if we need to schedule some disk IO
     update();
 }
+#endif  // HAL_GCS_ENABLED
 
 
 #endif // AP_TERRAIN_AVAILABLE