diff --git a/docs/Plugins.rst b/docs/Plugins.rst
index 082dff360..03ccd809f 100644
--- a/docs/Plugins.rst
+++ b/docs/Plugins.rst
@@ -129,6 +129,7 @@ probe
 Can be used to determine tile properties like temperature.
 
 .. _prospect:
+.. _prospector:
 
 prospect
 ========
diff --git a/docs/changelog.txt b/docs/changelog.txt
index 927500af8..ee11c6123 100644
--- a/docs/changelog.txt
+++ b/docs/changelog.txt
@@ -43,6 +43,7 @@ changelog.txt uses a syntax similar to RST, with a few special sequences:
 
 ## Fixes
 - `tweak` max-wheelbarrow: fixed conflict with building renaming
+- `prospector`: fixed crash due to invalid vein materials
 
 ## Misc Improvements
 - `adv-rumors`: bound to Ctrl-A
diff --git a/plugins/prospector.cpp b/plugins/prospector.cpp
index 18efeac98..fd2d959eb 100644
--- a/plugins/prospector.cpp
+++ b/plugins/prospector.cpp
@@ -177,16 +177,21 @@ void printVeins(color_ostream &con, MatMap &mat_map,
     MatMap gems;
     MatMap rest;
 
-    for (MatMap::const_iterator it = mat_map.begin(); it != mat_map.end(); ++it)
+    for (const auto &kv : mat_map)
     {
-        df::inorganic_raw *gloss = world->raws.inorganics[it->first];
+        df::inorganic_raw *gloss = vector_get(world->raws.inorganics, kv.first);
+        if (!gloss)
+        {
+            con.printerr("invalid material gloss: %hi\n", kv.first);
+            continue;
+        }
 
         if (gloss->material.isGem())
-            gems[it->first] = it->second;
+            gems[kv.first] = kv.second;
         else if (gloss->isOre())
-            ores[it->first] = it->second;
+            ores[kv.first] = kv.second;
         else
-            rest[it->first] = it->second;
+            rest[kv.first] = kv.second;
     }
 
     con << "Ores:" << std::endl;