diff --git a/cola/libdialect/io.cpp b/cola/libdialect/io.cpp
index ecbc0c3f..d8084d50 100644
--- a/cola/libdialect/io.cpp
+++ b/cola/libdialect/io.cpp
@@ -70,6 +70,8 @@ Graph_SP dialect::buildGraphFromTglf(istream &in) {
     while (getline(in, line)) {
         // Skip empty lines.
         if (line.empty()) continue;
+        // Comment lines begin with "//". (See https://stackoverflow.com/a/40441240)
+        if (line.rfind("//", 0) == 0) continue;
         // Check for "#" lines.
         if (line == "#") {
             // Time to change state.
diff --git a/cola/libdialect/io.h b/cola/libdialect/io.h
index 02be7074..e32fa474 100644
--- a/cola/libdialect/io.h
+++ b/cola/libdialect/io.h
@@ -40,6 +40,7 @@ class Graph;
  *
  * TGLF looks like this:
  *
+ * // This line is a comment.
  * i0 cx0 cy0 w0 h0
  * i1 cx1 cy1 w1 h1
  * ...