diff --git a/Changes b/Changes
index 6240d3fd2..dae018552 100644
--- a/Changes
+++ b/Changes
@@ -9,6 +9,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ****  Fix compile issues on MSVCC, bug571, bug577.  [Amir Gonnen]
 
+****  Fix --debug overriding preceding --dump-treei, bug580.  [Jeremy Bennett]
+
 
 * Verilator 3.842 2012/11/03
 
diff --git a/bin/verilator b/bin/verilator
index ab946c061..732ed12ff 100755
--- a/bin/verilator
+++ b/bin/verilator
@@ -573,6 +573,7 @@ Rarely needed.  Enable internal debugging assertion checks, without
 changing debug verbosity.  Enabled automatically when --debug specified.
 
 =item --debugi <level>
+
 =item --debugi-<srcfile> <level>
 
 Rarely needed - for developer use.  Set internal debugging level globally
@@ -612,7 +613,7 @@ the Verilator Internals manual.  --dump-tree is enabled automatically with
 --debug, so "--debug --no-dump-tree" may be useful if the dump files are
 large and not desired.
 
-=item --dump-treei
+=item --dump-treei <level>
 
 Rarely needed.  Enable writing .tree debug files with a specific dumping
 level, 0 disbles dumps and is equivelent to "--no-dump-tree".  Level 9
diff --git a/src/V3Options.cpp b/src/V3Options.cpp
index 1ac2f37bf..7b3bbbf5f 100644
--- a/src/V3Options.cpp
+++ b/src/V3Options.cpp
@@ -1243,7 +1243,7 @@ V3Options::~V3Options() {
 
 void V3Options::setDebugMode(int level) {
     V3Error::debugDefault(level);
-    m_dumpTree = true;
+    if (!m_dumpTree) m_dumpTree = true;	// Don't override if already set.
     m_stats = true;
     m_debugCheck = true;
     cout << "Starting "<<version()<<endl;