diff --git a/src/debug/debug.cpp b/src/debug/debug.cpp
index c438a3dc..d9047fc9 100644
--- a/src/debug/debug.cpp
+++ b/src/debug/debug.cpp
@@ -21,7 +21,7 @@
 #include <list>
 
 #include "dosbox.h"
-#ifdef C_DEBUG
+#if C_DEBUG
 #include "debug.h"
 #include "cpu.h"
 #include "video.h"
diff --git a/src/debug/debug_disasm.cpp b/src/debug/debug_disasm.cpp
index 87d35ef0..42cd96db 100644
--- a/src/debug/debug_disasm.cpp
+++ b/src/debug/debug_disasm.cpp
@@ -63,7 +63,7 @@ Any comments/updates/bug reports to:
 
 */
 #include "dosbox.h"
-#ifdef C_DEBUG
+#if C_DEBUG
 #include <stdio.h>
 #include <string.h>
 #include <stdarg.h>
diff --git a/src/debug/debug_gui.cpp b/src/debug/debug_gui.cpp
index c13f306e..86ddc92a 100644
--- a/src/debug/debug_gui.cpp
+++ b/src/debug/debug_gui.cpp
@@ -19,7 +19,7 @@
 
 
 #include "dosbox.h"
-#ifdef C_DEBUG
+#if C_DEBUG
 
 #include <stdlib.h>
 #include <stdarg.h>