diff --git a/src/engine/engine_print.c b/src/engine/engine_print.c
index c83a5123..396d04da 100644
--- a/src/engine/engine_print.c
+++ b/src/engine/engine_print.c
@@ -344,7 +344,7 @@ static void printVector(const char* str, const mjtNum* data, int n, FILE* fp,
 
 // print human readable memory size
 static const char* memorySize(size_t nbytes) {
-  static mjTHREADLOCAL char message[20];
+  static mjTHREADLOCAL char message[32];
   int k = 1024;
 
   if (nbytes < k) {