diff --git a/libyul/optimiser/Suite.cpp b/libyul/optimiser/Suite.cpp
index 4a175eb02..1a0628b00 100644
--- a/libyul/optimiser/Suite.cpp
+++ b/libyul/optimiser/Suite.cpp
@@ -67,6 +67,7 @@
 
 #include <libsolutil/CommonData.h>
 
+#include <boost/range/adaptor/map.hpp>
 #include <boost/range/algorithm_ext/erase.hpp>
 
 using namespace std;
@@ -235,6 +236,12 @@ map<string, char> const& OptimiserSuite::stepNameToAbbreviationMap()
 		{VarDeclInitializer::name,            'd'},
 	};
 	yulAssert(lookupTable.size() == allSteps().size(), "");
+	yulAssert((
+			util::convertContainer<set<char>>(string(NonStepAbbreviations)) -
+			util::convertContainer<set<char>>(lookupTable | boost::adaptors::map_values)
+		).size() == string(NonStepAbbreviations).size(),
+		"Step abbreviation conflicts with a character reserved for another syntactic element"
+	);
 
 	return lookupTable;
 }
@@ -265,6 +272,10 @@ void OptimiserSuite::runSequence(string const& _stepAbbreviations, Block& _ast)
 			insideLoop = false;
 			break;
 		default:
+			yulAssert(
+				string(NonStepAbbreviations).find(abbreviation) == string::npos,
+				"Unhandled syntactic element in the abbreviation sequence"
+			);
 			assertThrow(
 				stepAbbreviationToNameMap().find(abbreviation) != stepAbbreviationToNameMap().end(),
 				OptimizerException,
diff --git a/libyul/optimiser/Suite.h b/libyul/optimiser/Suite.h
index 3b0ed0163..e8a6c7a56 100644
--- a/libyul/optimiser/Suite.h
+++ b/libyul/optimiser/Suite.h
@@ -47,6 +47,10 @@ class OptimiserSuite
 public:
 	static constexpr size_t MaxRounds = 12;
 
+	/// Special characters that do not represent optimiser steps but are allowed in abbreviation sequences.
+	/// Some of them (like whitespace) are ignored, others (like brackets) are a part of the syntax.
+	static constexpr char NonStepAbbreviations[] = " \n[]";
+
 	enum class Debug
 	{
 		None,