diff --git a/src/gl/data/gl_setup.cpp b/src/gl/data/gl_setup.cpp
index 376b4aa6d..3b72c9863 100644
--- a/src/gl/data/gl_setup.cpp
+++ b/src/gl/data/gl_setup.cpp
@@ -302,9 +302,9 @@ static void PrepareSectorData()
 static void PrepareTransparentDoors(sector_t * sector)
 {
 	bool solidwall=false;
-	int notextures=0;
-	int nobtextures=0;
-	int selfref=0;
+	unsigned int notextures=0;
+	unsigned int nobtextures=0;
+	unsigned int selfref=0;
 	sector_t * nextsec=NULL;
 
 #ifdef _DEBUG
diff --git a/src/gl/dynlights/gl_glow.cpp b/src/gl/dynlights/gl_glow.cpp
index e0ed6d0f6..aaf3930e6 100644
--- a/src/gl/dynlights/gl_glow.cpp
+++ b/src/gl/dynlights/gl_glow.cpp
@@ -125,7 +125,7 @@ int gl_CheckSpriteGlow(sector_t *sector, int lightlevel, const DVector3 &pos)
 			}
 		}
 	}
-	else if (c != -1)
+	else if (uint32(-1) != c)
 	{
 		bottomglowcolor[0] = c.r / 255.f;
 		bottomglowcolor[1] = c.g / 255.f;
@@ -171,7 +171,7 @@ bool gl_GetWallGlow(sector_t *sector, float *topglowcolor, float *bottomglowcolo
 			}
 		}
 	}
-	else if (c != -1)
+	else if (uint32(-1) != c)
 	{
 		topglowcolor[0] = c.r / 255.f;
 		topglowcolor[1] = c.g / 255.f;
@@ -195,7 +195,7 @@ bool gl_GetWallGlow(sector_t *sector, float *topglowcolor, float *bottomglowcolo
 			}
 		}
 	}
-	else if (c != -1)
+	else if (uint32(-1) != c)
 	{
 		bottomglowcolor[0] = c.r / 255.f;
 		bottomglowcolor[1] = c.g / 255.f;
@@ -214,4 +214,4 @@ CCMD(setglow)
 	auto s = players[0].mo->Sector;
 	s->planes[sector_t::floor].GlowHeight = 128;
 	s->planes[sector_t::floor].GlowColor = 0xff0000;
-}
\ No newline at end of file
+}
diff --git a/src/gl/renderer/gl_colormap.h b/src/gl/renderer/gl_colormap.h
index 8bee402c9..2c9fb91a4 100644
--- a/src/gl/renderer/gl_colormap.h
+++ b/src/gl/renderer/gl_colormap.h
@@ -5,7 +5,7 @@
 #include "v_palette.h"
 #include "r_data/colormaps.h"
 
-extern DWORD gl_fixedcolormap;
+extern int gl_fixedcolormap;
 
 struct lightlist_t;
 
diff --git a/src/gl/renderer/gl_lightdata.h b/src/gl/renderer/gl_lightdata.h
index a1abf8c82..7af5e7a4f 100644
--- a/src/gl/renderer/gl_lightdata.h
+++ b/src/gl/renderer/gl_lightdata.h
@@ -35,7 +35,7 @@ inline bool gl_isWhite(PalEntry color)
 	return color.r + color.g + color.b == 3*0xff;
 }
 
-extern DWORD gl_fixedcolormap;
+extern int gl_fixedcolormap;
 
 inline bool gl_isFullbright(PalEntry color, int lightlevel)
 {
@@ -61,4 +61,4 @@ inline void FColormap::CopyFrom3DLight(lightlist_t *light)
 
 
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index f35071854..30c0000d3 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -323,7 +323,7 @@ void FGLRenderer::UpdateCameraExposure()
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 
 	// Find the average value:
-	for (int i = 0; i + 1 < mBuffers->ExposureLevels.Size(); i++)
+	for (unsigned int i = 0; i + 1 < mBuffers->ExposureLevels.Size(); i++)
 	{
 		const auto &level = mBuffers->ExposureLevels[i];
 		const auto &next = mBuffers->ExposureLevels[i + 1];
diff --git a/src/gl/renderer/gl_renderbuffers.cpp b/src/gl/renderer/gl_renderbuffers.cpp
index b14ee9852..77e77bf5b 100644
--- a/src/gl/renderer/gl_renderbuffers.cpp
+++ b/src/gl/renderer/gl_renderbuffers.cpp
@@ -448,7 +448,7 @@ void FGLRenderBuffers::CreateExposureLevels(int width, int height)
 
 void FGLRenderBuffers::CreateEyeBuffers(int eye)
 {
-	if (mEyeFBs.Size() > eye)
+	if (mEyeFBs.Size() > unsigned(eye))
 		return;
 
 	GLint activeTex, textureBinding, frameBufferBinding;
@@ -457,7 +457,7 @@ void FGLRenderBuffers::CreateEyeBuffers(int eye)
 	glGetIntegerv(GL_TEXTURE_BINDING_2D, &textureBinding);
 	glGetIntegerv(GL_FRAMEBUFFER_BINDING, &frameBufferBinding);
 
-	while (mEyeFBs.Size() <= eye)
+	while (mEyeFBs.Size() <= unsigned(eye))
 	{
 		GLuint texture = Create2DTexture("EyeTexture", GL_RGBA16F, mWidth, mHeight);
 		mEyeTextures.Push(texture);
diff --git a/src/gl/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index bedd7a7e7..b4efe736e 100644
--- a/src/gl/scene/gl_scene.cpp
+++ b/src/gl/scene/gl_scene.cpp
@@ -88,7 +88,7 @@ extern int viewpitch;
 extern bool NoInterpolateView;
 extern bool r_showviewer;
 
-DWORD			gl_fixedcolormap;
+int			gl_fixedcolormap;
 area_t			in_area;
 TArray<BYTE> currentmapsection;
 int camtexcount;
diff --git a/src/gl/scene/gl_walls.cpp b/src/gl/scene/gl_walls.cpp
index 4d258b3a0..5ac29dcad 100644
--- a/src/gl/scene/gl_walls.cpp
+++ b/src/gl/scene/gl_walls.cpp
@@ -1245,7 +1245,7 @@ void GLWall::ClipFFloors(seg_t * seg, F3DFloor * ffloor, sector_t * frontsector,
 {
 	TArray<F3DFloor *> & frontffloors = frontsector->e->XFloor.ffloors;
 
-	int flags = ffloor->flags & (FF_SWIMMABLE | FF_TRANSLUCENT);
+	const unsigned int flags = ffloor->flags & (FF_SWIMMABLE | FF_TRANSLUCENT);
 
 	for (unsigned int i = 0; i < frontffloors.Size(); i++)
 	{
diff --git a/src/gl/system/gl_debug.cpp b/src/gl/system/gl_debug.cpp
index a8b1bab5d..25651721e 100644
--- a/src/gl/system/gl_debug.cpp
+++ b/src/gl/system/gl_debug.cpp
@@ -143,7 +143,7 @@ void FGLDebug::SetupBreakpointMode()
 
 void FGLDebug::UpdateLoggingLevel()
 {
-	int level = gl_debug_level;
+	const GLenum level = gl_debug_level;
 	if (level != mCurrentLevel)
 	{
 		glDebugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_HIGH, 0, nullptr, level > 0);
diff --git a/src/gl/textures/gl_material.cpp b/src/gl/textures/gl_material.cpp
index 4be2e9619..8bb8ee6f0 100644
--- a/src/gl/textures/gl_material.cpp
+++ b/src/gl/textures/gl_material.cpp
@@ -285,7 +285,7 @@ const FHardwareTexture *FGLTexture::Bind(int texunit, int clampmode, int transla
 	if (translation <= 0) translation = -translation;
 	else
 	{
-		alphatrans = (gl.legacyMode && translation == TRANSLATION(TRANSLATION_Standard, 8));
+		alphatrans = (gl.legacyMode && DWORD(translation) == TRANSLATION(TRANSLATION_Standard, 8));
 		translation = GLTranslationPalette::GetInternalTranslation(translation);
 	}
 
diff --git a/src/p_setup.cpp b/src/p_setup.cpp
index de8357764..a1422236a 100644
--- a/src/p_setup.cpp
+++ b/src/p_setup.cpp
@@ -3088,7 +3088,7 @@ line_t**				linebuffer;
 static void P_GroupLines (bool buildmap)
 {
 	cycle_t times[16];
-	int*				linesDoneInEachSector;
+	unsigned int*		linesDoneInEachSector;
 	int 				i;
 	int 				total;
 	line_t* 			li;
@@ -3156,7 +3156,7 @@ static void P_GroupLines (bool buildmap)
 	times[3].Clock();
 	linebuffer = new line_t *[total];
 	line_t **lineb_p = linebuffer;
-	linesDoneInEachSector = new int[numsectors];
+	linesDoneInEachSector = new unsigned int[numsectors];
 	memset (linesDoneInEachSector, 0, sizeof(int)*numsectors);
 
 	for (sector = sectors, i = 0; i < numsectors; i++, sector++)
diff --git a/src/p_udmf.cpp b/src/p_udmf.cpp
index 51bd780f5..9f920d225 100644
--- a/src/p_udmf.cpp
+++ b/src/p_udmf.cpp
@@ -1695,7 +1695,7 @@ public:
 			sec->ceilingplane.set(n.X, n.Y, n.Z, cp[3]);
 		}
 
-		if (lightcolor == -1 && fadecolor == -1 && desaturation == -1 && fogdensity == -1)
+		if (lightcolor == uint32(-1) && fadecolor == uint32(-1) && desaturation == -1 && fogdensity == -1)
 		{
 			// [RH] Sectors default to white light with the default fade.
 			//		If they are outside (have a sky ceiling), they use the outside fog.
@@ -1714,8 +1714,8 @@ public:
 		}
 		else
 		{
-			if (lightcolor == -1) lightcolor = PalEntry(255,255,255);
-			if (fadecolor == -1)
+			if (uint32(-1) == lightcolor) lightcolor = PalEntry(255,255,255);
+			if (uint32(-1) == fadecolor)
 			{
 				if (level.outsidefog != 0xff000000 && (sec->GetTexture(sector_t::ceiling) == skyflatnum || (sec->special & 0xff) == Sector_Outside))
 					fadecolor = level.outsidefog;