diff --git a/progress.cpp b/progress.cpp
index ceceb44..c7c210b 100644
--- a/progress.cpp
+++ b/progress.cpp
@@ -1,5 +1,6 @@
 #include <iostream>
 #include <ctime>
+#include <cstdlib>
 #include <libscterm.hpp>
 
 void show_rows_cols(const sc::term& t) {
@@ -117,6 +118,10 @@ void show_words() {
 }
 
 void show_truecolor(const sc::term& t) {
+    // check for true color support
+    char* support = getenv("COLORTERM");
+    if (!support || support[0] == '\0') return;
+
     const char* lhb = u8"\u2584"; // lower half block
     int inc = 6.0 * t.cols() / 256.0;
     if (inc == 0) inc = 1;