diff --git a/changelog b/changelog
index 035bfa417320..49f56a97a5ec 100644
--- a/changelog
+++ b/changelog
@@ -73,6 +73,7 @@ Version 1.11.15+dev:
    * Fix bug in Random Recruit Micro AI: the AI can now handle custom castle
      terrain independent of its terrain code
    * Fix bug in Return Guardian Micro AI when there is no path to the return hex
+   * Fix bug #20126: Recursive preprocessor includes cause infinite loop
 
 Version 1.11.15:
  * Graphics:
diff --git a/src/serialization/preprocessor.cpp b/src/serialization/preprocessor.cpp
index 6f7638ab3750..f298d085fcaf 100644
--- a/src/serialization/preprocessor.cpp
+++ b/src/serialization/preprocessor.cpp
@@ -1053,7 +1053,7 @@ bool preprocessor_data::get_chunk()
 				pop_token();
 				put(v.str());
 			}
-			else if ((macro = target_.defines_->find(symbol)) != target_.defines_->end())
+			else if (target_.depth_ < 100 && (macro = target_.defines_->find(symbol)) != target_.defines_->end())
 			{
 				preproc_define const &val = macro->second;
 				size_t nb_arg = strings_.size() - token.stack_pos - 1;