diff --git a/Outputs/CRT/CRT.cpp b/Outputs/CRT/CRT.cpp
index 5b45513ea..6d2f17f4a 100644
--- a/Outputs/CRT/CRT.cpp
+++ b/Outputs/CRT/CRT.cpp
@@ -407,7 +407,8 @@ void CRT::set_immediate_default_phase(float phase) {
 
 void CRT::output_data(int number_of_cycles, size_t number_of_samples) {
 #ifndef NDEBUG
-	assert(number_of_samples <= allocated_data_length_);
+	assert(number_of_samples > 0 && number_of_samples <= allocated_data_length_);
+	allocated_data_length_ = std::numeric_limits<size_t>::min();
 #endif
 	scan_target_->end_data(number_of_samples);
 	Scan scan;
diff --git a/Outputs/CRT/CRT.hpp b/Outputs/CRT/CRT.hpp
index dd5985444..1982e378b 100644
--- a/Outputs/CRT/CRT.hpp
+++ b/Outputs/CRT/CRT.hpp
@@ -10,6 +10,7 @@
 #define CRT_hpp
 
 #include <cstdint>
+#include <limits>
 #include <memory>
 
 #include "../ScanTarget.hpp"
@@ -84,7 +85,7 @@ class CRT {
 		static const uint8_t DefaultAmplitude = 80;
 
 #ifndef NDEBUG
-		size_t allocated_data_length_ = 0;
+		size_t allocated_data_length_ = std::numeric_limits<size_t>::min();
 #endif
 
 	public: