diff --git a/src/mapgen/mapgen.cpp b/src/mapgen/mapgen.cpp
index 79c429ff6..6c426ba41 100644
--- a/src/mapgen/mapgen.cpp
+++ b/src/mapgen/mapgen.cpp
@@ -629,6 +629,13 @@ MapgenBasic::MapgenBasic(int mapgenid, MapgenParams *params, EmergeManager *emer
 	// Lava falls back to water as both are suitable as cave liquids.
 	if (c_lava_source == CONTENT_IGNORE)
 		c_lava_source = c_water_source;
+
+	if (c_stone == CONTENT_IGNORE)
+		errorstream << "Mapgen: Mapgen alias 'mapgen_stone' is invalid!" << std::endl;
+	if (c_water_source == CONTENT_IGNORE)
+		errorstream << "Mapgen: Mapgen alias 'mapgen_water_source' is invalid!" << std::endl;
+	if (c_river_water_source == CONTENT_IGNORE)
+		warningstream << "Mapgen: Mapgen alias 'mapgen_river_water_source' is invalid!" << std::endl;
 }
 
 
diff --git a/src/mapgen/mapgen_v6.cpp b/src/mapgen/mapgen_v6.cpp
index 653adc8ec..8a863c044 100644
--- a/src/mapgen/mapgen_v6.cpp
+++ b/src/mapgen/mapgen_v6.cpp
@@ -132,6 +132,21 @@ MapgenV6::MapgenV6(MapgenV6Params *params, EmergeManager *emerge)
 		c_stair_cobble = c_cobble;
 	if (c_stair_desert_stone == CONTENT_IGNORE)
 		c_stair_desert_stone = c_desert_stone;
+
+	if (c_stone == CONTENT_IGNORE)
+		errorstream << "Mapgen v6: Mapgen alias 'mapgen_stone' is invalid!" << std::endl;
+	if (c_dirt == CONTENT_IGNORE)
+		errorstream << "Mapgen v6: Mapgen alias 'mapgen_dirt' is invalid!" << std::endl;
+	if (c_dirt_with_grass == CONTENT_IGNORE)
+		errorstream << "Mapgen v6: Mapgen alias 'mapgen_dirt_with_grass' is invalid!" << std::endl;
+	if (c_sand == CONTENT_IGNORE)
+		errorstream << "Mapgen v6: Mapgen alias 'mapgen_sand' is invalid!" << std::endl;
+	if (c_water_source == CONTENT_IGNORE)
+		errorstream << "Mapgen v6: Mapgen alias 'mapgen_water_source' is invalid!" << std::endl;
+	if (c_lava_source == CONTENT_IGNORE)
+		errorstream << "Mapgen v6: Mapgen alias 'mapgen_lava_source' is invalid!" << std::endl;
+	if (c_cobble == CONTENT_IGNORE)
+		errorstream << "Mapgen v6: Mapgen alias 'mapgen_cobble' is invalid!" << std::endl;
 }
 
 
diff --git a/src/mapgen/treegen.cpp b/src/mapgen/treegen.cpp
index 0d8af2851..89bdef73b 100644
--- a/src/mapgen/treegen.cpp
+++ b/src/mapgen/treegen.cpp
@@ -44,6 +44,12 @@ void make_tree(MMVManip &vmanip, v3s16 p0, bool is_apple_tree,
 	MapNode treenode(ndef->getId("mapgen_tree"));
 	MapNode leavesnode(ndef->getId("mapgen_leaves"));
 	MapNode applenode(ndef->getId("mapgen_apple"));
+	if (treenode == CONTENT_IGNORE)
+		errorstream << "Treegen: Mapgen alias 'mapgen_tree' is invalid!" << std::endl;
+	if (leavesnode == CONTENT_IGNORE)
+		errorstream << "Treegen: Mapgen alias 'mapgen_leaves' is invalid!" << std::endl;
+	if (applenode == CONTENT_IGNORE)
+		errorstream << "Treegen: Mapgen alias 'mapgen_apple' is invalid!" << std::endl;
 
 	PseudoRandom pr(seed);
 	s16 trunk_h = pr.range(4, 5);
@@ -145,6 +151,9 @@ treegen::error make_ltree(MMVManip &vmanip, v3s16 p0,
 	const NodeDefManager *ndef, TreeDef tree_definition)
 {
 	MapNode dirtnode(ndef->getId("mapgen_dirt"));
+	if (dirtnode == CONTENT_IGNORE)
+		errorstream << "Treegen (make_ltree): Mapgen alias 'mapgen_dirt' is invalid!" << std::endl;
+
 	s32 seed;
 	if (tree_definition.explicit_seed)
 		seed = tree_definition.seed + 14002;
@@ -662,6 +671,10 @@ void make_jungletree(MMVManip &vmanip, v3s16 p0, const NodeDefManager *ndef,
 		c_tree = ndef->getId("mapgen_tree");
 	if (c_leaves == CONTENT_IGNORE)
 		c_leaves = ndef->getId("mapgen_leaves");
+	if (c_tree == CONTENT_IGNORE)
+		errorstream << "Treegen: Mapgen alias 'mapgen_jungletree' is invalid!" << std::endl;
+	if (c_leaves == CONTENT_IGNORE)
+		errorstream << "Treegen: Mapgen alias 'mapgen_jungleleaves' is invalid!" << std::endl;
 
 	MapNode treenode(c_tree);
 	MapNode leavesnode(c_leaves);
@@ -765,6 +778,10 @@ void make_pine_tree(MMVManip &vmanip, v3s16 p0, const NodeDefManager *ndef,
 		c_leaves = ndef->getId("mapgen_leaves");
 	if (c_snow == CONTENT_IGNORE)
 		c_snow = CONTENT_AIR;
+	if (c_tree == CONTENT_IGNORE)
+		errorstream << "Treegen: Mapgen alias 'mapgen_pine_tree' is invalid!" << std::endl;
+	if (c_leaves == CONTENT_IGNORE)
+		errorstream << "Treegen: Mapgen alias 'mapgen_pine_needles' is invalid!" << std::endl;
 
 	MapNode treenode(c_tree);
 	MapNode leavesnode(c_leaves);