diff --git a/similar/main/inferno.cpp b/similar/main/inferno.cpp
index c98e4bdfa..c561b39a9 100644
--- a/similar/main/inferno.cpp
+++ b/similar/main/inferno.cpp
@@ -129,9 +129,19 @@ static void print_commandline_help()
 
 #define DXX_if_defined_placeholder1	,
 #define DXX_if_defined_unwrap(A,...)	A, ## __VA_ARGS__
+	/* If the parameter V, after macro expansion, evaluates to `1`, then
+	 * expand to the parameter F.  Otherwise, expand to nothing.
+	 */
 #define DXX_if_defined(V,F)	DXX_if_defined2(V,F)
+	/* If the parameter V, after macro expansion, evaluates to anything
+	 * other than `1`, then expand to the parameter F.  Otherwise,
+	 * expand to nothing.
+	 */
+#define DXX_if_not_defined_to_1(V,F)	DXX_if_not_defined_to_1_2(V,F)
 #define DXX_if_defined2(V,F)	DXX_if_defined3(DXX_if_defined_placeholder##V, F)
+#define DXX_if_not_defined_to_1_2(V,F)	DXX_if_not_defined_to_1_3(DXX_if_defined_placeholder##V, F)
 #define DXX_if_defined3(V,F)	DXX_if_defined4(F, V 1, 0)
+#define DXX_if_not_defined_to_1_3(V,F)	DXX_if_defined4(F, V 0, 1)
 #define DXX_if_defined4(F,_,V,...)	DXX_if_defined5_##V(F)
 #define DXX_if_defined5_0(F)
 #define DXX_if_defined5_1(F)	DXX_if_defined_unwrap F
@@ -205,11 +215,13 @@ static void print_commandline_help()
 		VERB("                                    5: Auto: if VSync is enabled and ARB_sync is supported, use mode 2, otherwise mode 0\n")	\
 		VERB("  -gl_syncwait <n>              Wait interval (ms) for sync mode 2 (default: " DXX_STRINGIZE(OGL_SYNC_WAIT_DEFAULT) ")\n")	\
 		VERB("  -gl_darkedges                 Re-enable dark edges around filtered textures (as present in earlier versions of the engine)\n")	\
+		DXX_if_not_defined_to_1(RELEASE, (	\
 		VERB("  -gl_stereo                    Enable OpenGL stereo quad buffering, if available\n")	\
-		VERB("  -gl_stereoview <n>            Select OpenGL stereo viewport mode\n")	\
+		VERB("  -gl_stereoview <n>            Select OpenGL stereo viewport mode (experimental; incomplete)\n")	\
 		VERB("                                    1: above/below half-height format\n")	\
 		VERB("                                    2: side/by/side half-width format\n")	\
 		VERB("                                    3: side/by/side half-size format, normal aspect ratio\n") \
+	))	\
 	)	\
 	DXX_if_defined_01(DXX_USE_UDP, (	\
 		VERB("\n Multiplayer:\n\n")	\