diff --git a/src/cmdlib.cpp b/src/cmdlib.cpp
index 557c80cf8..b3c406ee0 100644
--- a/src/cmdlib.cpp
+++ b/src/cmdlib.cpp
@@ -957,7 +957,7 @@ void ScanDirectory(TArray<FFileList> &list, const char *dirpath)
 	}
 }
 
-#elif defined(__sun) || defined(linux)
+#elif defined(__sun) || defined(__linux__)
 
 //==========================================================================
 //
diff --git a/src/gl/data/gl_portaldata.cpp b/src/gl/data/gl_portaldata.cpp
index 11989b4a7..676f6a630 100644
--- a/src/gl/data/gl_portaldata.cpp
+++ b/src/gl/data/gl_portaldata.cpp
@@ -223,7 +223,7 @@ struct FCoverageBuilder
 			{
 				FCoverageVertex *v1 = &shape[i];
 				FCoverageVertex *v2 = &shape[(i+1) % shape.Size()];
-				FCoverageLine vl = { *v1, *v2 };
+				FCoverageLine vl = {{*v1, *v2}};
 
 				double dist_v1 = PartitionDistance(v1, bsp);
 				double dist_v2 = PartitionDistance(v2, bsp);
diff --git a/src/gl/data/gl_setup.cpp b/src/gl/data/gl_setup.cpp
index d822ac440..342f58fa1 100644
--- a/src/gl/data/gl_setup.cpp
+++ b/src/gl/data/gl_setup.cpp
@@ -130,7 +130,7 @@ static int MergeMapSections(int num)
 	cvertex_t vt;
 
 	// first step: Set mapsection for all vertex positions.
-	for(DWORD i=0;i<numsegs;i++)
+	for(DWORD i=0;i<(DWORD)numsegs;i++)
 	{
 		seg_t * seg = &segs[i];
 		int section = seg->Subsector->mapsection;
@@ -142,7 +142,7 @@ static int MergeMapSections(int num)
 	}
 
 	// second step: Check if any seg references more than one mapsection, either by subsector or by vertex
-	for(DWORD i=0;i<numsegs;i++)
+	for(DWORD i=0;i<(DWORD)numsegs;i++)
 	{
 		seg_t * seg = &segs[i];
 		int section = seg->Subsector->mapsection;
@@ -733,4 +733,4 @@ CCMD(listmapsections)
 			}
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/src/gl/scene/gl_portal.cpp b/src/gl/scene/gl_portal.cpp
index 95ab7b567..3d9c8627d 100644
--- a/src/gl/scene/gl_portal.cpp
+++ b/src/gl/scene/gl_portal.cpp
@@ -781,7 +781,7 @@ void GLPlaneMirrorPortal::DrawContents()
 	gl.Enable(GL_CLIP_PLANE0+renderdepth);
 	// This only works properly for non-sloped planes so don't bother with the math.
 	//double d[4]={origin->a/65536., origin->c/65536., origin->b/65536., FIXED2FLOAT(origin->d)};
-	double d[4]={0, PlaneMirrorMode, 0, FIXED2FLOAT(origin->d)};
+	double d[4]={0, static_cast<double>(PlaneMirrorMode), 0, FIXED2FLOAT(origin->d)};
 	gl.ClipPlane(GL_CLIP_PLANE0+renderdepth, d);
 
 	GLRenderer->DrawScene();
diff --git a/src/gl/system/gl_interface.cpp b/src/gl/system/gl_interface.cpp
index 6789c2c20..964f623d7 100644
--- a/src/gl/system/gl_interface.cpp
+++ b/src/gl/system/gl_interface.cpp
@@ -44,7 +44,7 @@
 #include "i_system.h"
 #include "gl/system/gl_cvars.h"
 
-#if defined (unix) || defined (__APPLE__)
+#if defined (__unix__) || defined (__APPLE__)
 #include <SDL.h>
 #define wglGetProcAddress(x) (*SDL_GL_GetProcAddress)(x)
 #endif
@@ -210,7 +210,7 @@ void gl_LoadExtensions()
 	// Don't even start if it's lower than 1.4
 	if (strcmp(version, "1.4") < 0) 
 	{
-		I_FatalError("Unsupported OpenGL version.\nAt least GL 1.4 is required to run "GAMENAME".\n");
+		I_FatalError("Unsupported OpenGL version.\nAt least GL 1.4 is required to run " GAMENAME ".\n");
 	}
 
 	// This loads any function pointers and flags that require a vaild render context to
diff --git a/src/gl/textures/gl_material.cpp b/src/gl/textures/gl_material.cpp
index 53d01a3b9..f2d31ee0c 100644
--- a/src/gl/textures/gl_material.cpp
+++ b/src/gl/textures/gl_material.cpp
@@ -430,7 +430,7 @@ const FHardwareTexture *FGLTexture::Bind(int texunit, int cm, int clampmode, int
 		if (!hwtex->Bind(texunit, cm, translation))
 		{
 			
-			int w, h;
+			int w=0, h=0;
 
 			// Create this texture
 			unsigned char * buffer = NULL;
diff --git a/src/sdl/sdlglvideo.cpp b/src/sdl/sdlglvideo.cpp
index 868cf0afc..649989e6d 100644
--- a/src/sdl/sdlglvideo.cpp
+++ b/src/sdl/sdlglvideo.cpp
@@ -56,7 +56,7 @@ EXTERN_CVAR (Int, vid_renderer)
 
 CUSTOM_CVAR(Int, gl_vid_multisample, 0, CVAR_ARCHIVE | CVAR_GLOBALCONFIG | CVAR_NOINITCALL )
 {
-	Printf("This won't take effect until "GAMENAME" is restarted.\n");
+	Printf("This won't take effect until " GAMENAME " is restarted.\n");
 }
 
 // PRIVATE DATA DEFINITIONS ------------------------------------------------