diff --git a/base/gameDetector.cpp b/base/gameDetector.cpp
index 917f7b0ff39..a3b1fcdc328 100644
--- a/base/gameDetector.cpp
+++ b/base/gameDetector.cpp
@@ -47,8 +47,6 @@
 #endif
 #endif
 
-extern int gDebugLevel;
-
 // DONT FIXME: DO NOT ORDER ALPHABETICALLY, THIS IS ORDERED BY IMPORTANCE/CATEGORY! :)
 #ifdef __PALM_OS__
 static const char USAGE_STRING[] = "NoUsageString"; // save more data segment space
@@ -378,7 +376,7 @@ void GameDetector::parseCommandLine(int argc, char **argv) {
 			END_OPTION
 			
 			DO_OPTION_OPT('d', "debuglevel")
-				gDebugLevel = option ? (int)strtol(option, 0, 10) : 1;
+				gDebugLevel = option ? (int)strtol(option, 0, 10) : 0;
 				printf("Debuglevel (from command line): %d\n", gDebugLevel);
 			END_OPTION
 			
diff --git a/base/main.cpp b/base/main.cpp
index d8afe0ddf7c..70ce2726bcf 100644
--- a/base/main.cpp
+++ b/base/main.cpp
@@ -185,8 +185,13 @@ static void do_memory_test(void) {
 
 #endif
 
-
-int gDebugLevel = 0;
+/**
+ * The debug level. Initially set to -1, indicating that no debug output
+ * should be shown. Positive values usually imply an increasing number of
+ * debug output shall be generated, the higher the value, the more verbose the
+ * information (although the exact semantics are up to the engines).
+ */
+int gDebugLevel = -1;
 
 static void setupDummyPalette(OSystem &system) {
 	// FIXME - mouse cursors are currently always set via 8 bit data.
diff --git a/scumm/debugger.cpp b/scumm/debugger.cpp
index 11d85d5e3ff..0b74138248a 100644
--- a/scumm/debugger.cpp
+++ b/scumm/debugger.cpp
@@ -596,10 +596,10 @@ bool ScummDebugger::Cmd_DebugLevel(int argc, const char **argv) {
 			DebugPrintf("Debugging is currently set at level %d\n", gDebugLevel);
 	} else { // set level
 		gDebugLevel = atoi(argv[1]);
-		if (gDebugLevel > 0) {
+		if (gDebugLevel >= 0) {
 			_vm->_debugMode = true;
 			DebugPrintf("Debug level set to level %d\n", gDebugLevel);
-		} else if (gDebugLevel == 0) {
+		} else if (gDebugLevel < 0) {
 			_vm->_debugMode = false;
 			DebugPrintf("Debugging is now disabled\n");
 		} else
diff --git a/scumm/scumm.cpp b/scumm/scumm.cpp
index 1ff99b974a9..d4d26ef3f68 100644
--- a/scumm/scumm.cpp
+++ b/scumm/scumm.cpp
@@ -1058,7 +1058,7 @@ ScummEngine::ScummEngine(GameDetector *detector, OSystem *syst, const ScummGameS
 	g_scumm = this;
 
 	// Read settings from the detector & config manager
-	_debugMode = (gDebugLevel > 0);
+	_debugMode = (gDebugLevel >= 0);
 	_dumpScripts = detector->_dumpScripts;
 	_bootParam = ConfMan.getInt("boot_param");
 
diff --git a/simon/debugger.cpp b/simon/debugger.cpp
index 8e59970a712..63522259ce5 100644
--- a/simon/debugger.cpp
+++ b/simon/debugger.cpp
@@ -90,10 +90,10 @@ bool Debugger::Cmd_DebugLevel(int argc, const char **argv) {
 			DebugPrintf("Debugging is currently set at level %d\n", gDebugLevel);
 	} else { // set level
 		gDebugLevel = atoi(argv[1]);
-		if (gDebugLevel > 0 && gDebugLevel < 10) {
+		if (gDebugLevel >= 0 && gDebugLevel < 10) {
 			_vm->_debugMode = true;
 			DebugPrintf("Debug level set to level %d\n", gDebugLevel);
-		} else if (gDebugLevel == 0) {
+		} else if (gDebugLevel < 0) {
 			_vm->_debugMode = false;
 			DebugPrintf("Debugging is now disabled\n");
 		} else
diff --git a/simon/simon.cpp b/simon/simon.cpp
index 7455d39b5c5..42c5d33666c 100644
--- a/simon/simon.cpp
+++ b/simon/simon.cpp
@@ -695,7 +695,7 @@ int SimonEngine::init(GameDetector &detector) {
 		warning ("MIDI Player init failed: \"%s\"", midi.getErrorName (ret));
 	midi.set_volume(ConfMan.getInt("music_volume"));
 
-	_debugMode = (gDebugLevel > 0);
+	_debugMode = (gDebugLevel >= 0);
 
 	if (ConfMan.hasKey("music_mute") && ConfMan.getBool("music_mute") == 1)
 		midi.pause(_music_paused ^= 1);