diff --git a/src/benchmark/benchmark_mapblock.cpp b/src/benchmark/benchmark_mapblock.cpp
index 440888d16..5522276f9 100644
--- a/src/benchmark/benchmark_mapblock.cpp
+++ b/src/benchmark/benchmark_mapblock.cpp
@@ -106,7 +106,8 @@ static u32 workOnBoth(const MBContainer &vec)
 	int foo = 0;
 	for (MapBlock *block : vec) {
 		block->contents.clear();
-		block->contents_cached = false;
+
+		bool want_contents_cached = block->contents.empty() && !block->do_not_cache_contents;
 
 		v3s16 p0;
 		for(p0.X=0; p0.X<MAP_BLOCKSIZE; p0.X++)
@@ -116,18 +117,18 @@ static u32 workOnBoth(const MBContainer &vec)
 			MapNode n = block->getNodeNoCheck(p0);
 			content_t c = n.getContent();
 
-			if (!block->contents_cached && !block->do_not_cache_contents) {
-				if (!CONTAINS(block->contents, c))
-					block->contents.push_back(c);
-				if (block->contents.size() > 10) {
-					// Too many different nodes... don't try to cache
+			if (want_contents_cached && !CONTAINS(block->contents, c)) {
+				if (block->contents.size() >= 10) {
+					want_contents_cached = false;
 					block->do_not_cache_contents = true;
 					block->contents.clear();
 					block->contents.shrink_to_fit();
+				} else {
+					block->contents.push_back(c);
 				}
 			}
 		}
-		block->contents_cached = !block->do_not_cache_contents;
+
 		foo += block->contents.size();
 	}
 	return foo;
diff --git a/src/mapblock.h b/src/mapblock.h
index 1778aef8b..16aaa1f28 100644
--- a/src/mapblock.h
+++ b/src/mapblock.h
@@ -114,7 +114,7 @@ public:
 			m_modified_reason |= reason;
 		}
 		if (mod == MOD_STATE_WRITE_NEEDED)
-			contents_cached = false;
+			contents.clear();
 	}
 
 	inline u32 getModified()
@@ -463,9 +463,8 @@ public:
 	// Cache of content types
 	// This is actually a set but for the small sizes we have a vector should be
 	// more efficient.
+	// Can be empty, in which case nothing was cached yet.
 	std::vector<content_t> contents;
-	// True if content types are cached
-	bool contents_cached = false;
 	// True if we never want to cache content types for this block
 	bool do_not_cache_contents = false;
 	// marks the sides which are opaque: 00+Z-Z+Y-Y+X-X
diff --git a/src/serverenvironment.cpp b/src/serverenvironment.cpp
index c4f8d1b13..810456b0d 100644
--- a/src/serverenvironment.cpp
+++ b/src/serverenvironment.cpp
@@ -894,7 +894,8 @@ public:
 		// Check the content type cache first
 		// to see whether there are any ABMs
 		// to be run at all for this block.
-		if (block->contents_cached) {
+		if (!block->contents.empty()) {
+			assert(!block->do_not_cache_contents); // invariant
 			blocks_cached++;
 			bool run_abms = false;
 			for (content_t c : block->contents) {
@@ -905,9 +906,6 @@ public:
 			}
 			if (!run_abms)
 				return;
-		} else {
-			// Clear any caching
-			block->contents.clear();
 		}
 		blocks_scanned++;
 
@@ -917,6 +915,8 @@ public:
 		u32 active_object_count = this->countObjects(block, map, active_object_count_wider);
 		m_env->m_added_objects = 0;
 
+		bool want_contents_cached = block->contents.empty() && !block->do_not_cache_contents;
+
 		v3s16 p0;
 		for(p0.X=0; p0.X<MAP_BLOCKSIZE; p0.X++)
 		for(p0.Y=0; p0.Y<MAP_BLOCKSIZE; p0.Y++)
@@ -926,14 +926,15 @@ public:
 			content_t c = n.getContent();
 
 			// Cache content types as we go
-			if (!block->contents_cached && !block->do_not_cache_contents) {
-				if (!CONTAINS(block->contents, c))
-					block->contents.push_back(c);
-				if (block->contents.size() > CONTENT_TYPE_CACHE_MAX) {
+			if (want_contents_cached && !CONTAINS(block->contents, c)) {
+				if (block->contents.size() >= CONTENT_TYPE_CACHE_MAX) {
 					// Too many different nodes... don't try to cache
+					want_contents_cached = false;
 					block->do_not_cache_contents = true;
 					block->contents.clear();
 					block->contents.shrink_to_fit();
+				} else {
+					block->contents.push_back(c);
 				}
 			}
 
@@ -997,7 +998,6 @@ public:
 					break;
 			}
 		}
-		block->contents_cached = !block->do_not_cache_contents;
 	}
 };