diff --git a/SourceGen/PlatformSymbols.cs b/SourceGen/PlatformSymbols.cs
index 65ab484..4039bfc 100644
--- a/SourceGen/PlatformSymbols.cs
+++ b/SourceGen/PlatformSymbols.cs
@@ -141,8 +141,9 @@ namespace SourceGen {
             int lineNum = 0;
             foreach (string line in lines) {
                 lineNum++;      // first line is line 1, says Vim and VisualStudio
-                if (string.IsNullOrEmpty(line) || line[0] == ';') {
-                    // ignore
+                string trimLine = line.Trim();
+                if (string.IsNullOrEmpty(trimLine) || trimLine[0] == ';') {
+                    // all whitespace, or just a comment; ignore
                 } else if (line[0] == '*') {
                     if (line.StartsWith(TAG_CMD)) {
                         tag = ParseTag(line);
diff --git a/SourceGen/SGTestData/20170-external-symbols-1.sym65 b/SourceGen/SGTestData/20170-external-symbols-1.sym65
index 2ee61e4..a553b13 100644
--- a/SourceGen/SGTestData/20170-external-symbols-1.sym65
+++ b/SourceGen/SGTestData/20170-external-symbols-1.sym65
@@ -121,3 +121,11 @@ TooLong         @   $c0f8   $a
 *MULTI_MASK $ffff $ffff $fffff  ;range
 
 *MULTI_MASK
+
+
+; The following lines have nothing but whitespace.
+ 
+     
+		
+  ;Comment with leading spaces.
+	;leading tab