diff --git a/README.md b/README.md
index 2bd663cf..0cb53b29 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,7 @@ State:
 Goals (none of it finished):
   * Single player support,
   * BSPX DECOUPLEDLM light map support (base1),
-  * IBSQ map format support (mguhub),
+  * QBSP map format support (mguhub),
   * MD5 model support,
   * modified ReRelease game code support with removed KEX only related code,
   * RoQ and Theora cinematic videos support.
diff --git a/src/client/refresh/gl1/gl1_model.c b/src/client/refresh/gl1/gl1_model.c
index 4c40b282..c536beaf 100644
--- a/src/client/refresh/gl1/gl1_model.c
+++ b/src/client/refresh/gl1/gl1_model.c
@@ -893,7 +893,7 @@ Mod_LoadBrushModel(model_t *mod, const void *buffer, int modfilelen)
 
 	i = LittleLong(header->ident);
 
-	if (i != IDBSPHEADER && i != QDBSPHEADER)
+	if (i != IDBSPHEADER && i != QBSPHEADER)
 	{
 		ri.Sys_Error(ERR_DROP, "%s: %s has wrong ident (%i should be %i)",
 				__func__, mod->name, i, IDBSPHEADER);
@@ -1129,7 +1129,7 @@ Mod_ForName(const char *name, model_t *parent_model, qboolean crash)
 
 		case IDBSPHEADER:
 			/* fall through */
-		case QDBSPHEADER:
+		case QBSPHEADER:
 			Mod_LoadBrushModel(mod, buf, modfilelen);
 			break;
 
diff --git a/src/client/refresh/gl3/gl3_model.c b/src/client/refresh/gl3/gl3_model.c
index e80fd265..ecad3a9f 100644
--- a/src/client/refresh/gl3/gl3_model.c
+++ b/src/client/refresh/gl3/gl3_model.c
@@ -818,7 +818,7 @@ Mod_LoadBrushModel(gl3model_t *mod, const void *buffer, int modfilelen)
 
 	i = LittleLong(header->ident);
 
-	if (i != IDBSPHEADER && i != QDBSPHEADER)
+	if (i != IDBSPHEADER && i != QBSPHEADER)
 	{
 		ri.Sys_Error(ERR_DROP, "%s: %s has wrong ident (%i should be %i)",
 				__func__, mod->name, i, IDBSPHEADER);
@@ -1054,7 +1054,7 @@ Mod_ForName (const char *name, gl3model_t *parent_model, qboolean crash)
 
 		case IDBSPHEADER:
 			/* fall through */
-		case QDBSPHEADER:
+		case QBSPHEADER:
 			Mod_LoadBrushModel(mod, buf, modfilelen);
 			break;
 
diff --git a/src/client/refresh/soft/sw_model.c b/src/client/refresh/soft/sw_model.c
index 89ab0fe9..75701f71 100644
--- a/src/client/refresh/soft/sw_model.c
+++ b/src/client/refresh/soft/sw_model.c
@@ -681,7 +681,7 @@ Mod_LoadBrushModel(model_t *mod, const void *buffer, int modfilelen)
 
 	i = LittleLong(header->ident);
 
-	if (i != IDBSPHEADER && i != QDBSPHEADER)
+	if (i != IDBSPHEADER && i != QBSPHEADER)
 	{
 		ri.Sys_Error(ERR_DROP, "%s: %s has wrong ident (%i should be %i)",
 				__func__, mod->name, i, IDBSPHEADER);
@@ -921,7 +921,7 @@ Mod_ForName(const char *name, model_t *parent_model, qboolean crash)
 
 		case IDBSPHEADER:
 			/* fall through */
-		case QDBSPHEADER:
+		case QBSPHEADER:
 			Mod_LoadBrushModel(mod, buf, modfilelen);
 			break;
 
diff --git a/src/client/refresh/vk/vk_model.c b/src/client/refresh/vk/vk_model.c
index 075c2757..cb085876 100644
--- a/src/client/refresh/vk/vk_model.c
+++ b/src/client/refresh/vk/vk_model.c
@@ -878,7 +878,7 @@ Mod_LoadBrushModel(model_t *mod, const void *buffer, int modfilelen)
 
 	i = LittleLong(header->ident);
 
-	if (i != IDBSPHEADER && i != QDBSPHEADER)
+	if (i != IDBSPHEADER && i != QBSPHEADER)
 	{
 		ri.Sys_Error(ERR_DROP, "%s: %s has wrong ident (%i should be %i)",
 				__func__, mod->name, i, IDBSPHEADER);
@@ -1125,7 +1125,7 @@ Mod_ForName (const char *name, model_t *parent_model, qboolean crash)
 
 	case IDBSPHEADER:
 		/* fall through */
-	case QDBSPHEADER:
+	case QBSPHEADER:
 		Mod_LoadBrushModel(mod, buf, modfilelen);
 		break;
 
diff --git a/src/common/collision.c b/src/common/collision.c
index f32c3828..d083d7fc 100644
--- a/src/common/collision.c
+++ b/src/common/collision.c
@@ -1937,7 +1937,7 @@ CM_LoadMap(char *name, qboolean clientload, unsigned *checksum)
 		((int *)&header)[i] = LittleLong(((int *)&header)[i]);
 	}
 
-	if (header.ident != IDBSPHEADER && header.ident != QDBSPHEADER)
+	if (header.ident != IDBSPHEADER && header.ident != QBSPHEADER)
 	{
 		Com_Error(ERR_DROP, "%s: %s has wrong ident (%i should be %i)",
 				__func__, name, header.ident, IDBSPHEADER);
diff --git a/src/common/header/files.h b/src/common/header/files.h
index 07c8cd47..71dcace0 100644
--- a/src/common/header/files.h
+++ b/src/common/header/files.h
@@ -350,8 +350,8 @@ typedef struct {
 /* .BSP file format */
 
 #define IDBSPHEADER (('P' << 24) + ('S' << 16) + ('B' << 8) + 'I') /* little-endian "IBSP" */
-#define QDBSPHEADER (('P' << 24) + ('S' << 16) + ('B' << 8) + 'Q') /* little-endian "IBSQ" */
-#define BSPXHEADER  (('X' << 24) + ('P' << 16) + ('S' << 8) + 'B') /* little-endian "BSPX" */
+#define QBSPHEADER (('P' << 24) + ('S' << 16) + ('B' << 8) + 'Q') /* little-endian "QBSP" */
+#define BSPXHEADER (('X' << 24) + ('P' << 16) + ('S' << 8) + 'B') /* little-endian "BSPX" */
 #define BSPVERSION 38
 #define BSPDKMVERSION 41