diff --git a/source/lib/glext_funcs.h b/source/lib/glext_funcs.h
index 6dff419260..a24a3c81e9 100644
--- a/source/lib/glext_funcs.h
+++ b/source/lib/glext_funcs.h
@@ -69,6 +69,9 @@ FUNC2(void, glMultiTexCoord3fARB, glMultiTexCoord3f, "1.3", (int, float, float,
 FUNC2(void, glActiveTextureARB, glActiveTexture, "1.3", (int))
 FUNC2(void, glClientActiveTextureARB, glClientActiveTexture, "1.3", (int))
 
+// GL_EXT_blend_color / GL1.4 (optional in 1.2):
+FUNC2(void, glBlendColorEXT, glBlendColor, "1.4", (GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha));
+
 // GL_ARB_vertex_buffer_object / GL1.5:
 FUNC2(void, glBindBufferARB, glBindBuffer, "1.5", (int target, GLuint buffer))
 FUNC2(void, glDeleteBuffersARB, glDeleteBuffers, "1.5", (GLsizei n, const GLuint* buffers))
diff --git a/source/lib/ogl.cpp b/source/lib/ogl.cpp
index 4e16a94e7f..442870aa10 100644
--- a/source/lib/ogl.cpp
+++ b/source/lib/ogl.cpp
@@ -145,6 +145,12 @@ static bool isImplementedInCore(const char* ext)
 		MATCH(GL_EXT_texture_lod_bias);
 		MATCH(GL_ARB_texture_mirrored_repeat);
 		MATCH(GL_ARB_window_pos);
+
+		// These extensions were added to GL 1.2, but as part of the optional
+		// imaging subset; they're only guaranteed as of GL 1.4:
+		MATCH(GL_EXT_blend_color);
+		MATCH(GL_EXT_blend_minmax);
+		MATCH(GL_EXT_blend_subtract);
 	}
 	if(have_13)
 	{
@@ -169,9 +175,6 @@ static bool isImplementedInCore(const char* ext)
 		MATCH(GL_SGIS_texture_lod);
 		MATCH(GL_EXT_draw_range_elements);
 		// Skip the extensions that only affect the imaging subset
-		MATCH(GL_EXT_blend_color);
-		MATCH(GL_EXT_blend_minmax);
-		MATCH(GL_EXT_blend_subtract);
 	}
 
 #undef MATCH
diff --git a/source/lib/sysdep/os/win/wsdl.cpp b/source/lib/sysdep/os/win/wsdl.cpp
index db61618f99..ebfe4e96cc 100644
--- a/source/lib/sysdep/os/win/wsdl.cpp
+++ b/source/lib/sysdep/os/win/wsdl.cpp
@@ -259,6 +259,7 @@ static HGLRC hGLRC = (HGLRC)INVALID_HANDLE_VALUE;
 
 // set via SDL_GL_SetAttribute:
 static int depthBufferBits = 24;
+static int stencilBufferBits = 0;
 static int vsyncEnabled = 1;
 
 int SDL_GL_SetAttribute(SDL_GLattr attr, int value)
@@ -269,6 +270,10 @@ int SDL_GL_SetAttribute(SDL_GLattr attr, int value)
 		depthBufferBits = value;
 		break;
 
+	case SDL_GL_STENCIL_SIZE:
+		stencilBufferBits = value;
+		break;
+
 	case SDL_GL_SWAP_CONTROL:
 		vsyncEnabled = value;
 		break;
@@ -313,7 +318,7 @@ static void video_SetPixelFormat(HDC g_hDC, int bpp)
 	}
 	const BYTE cAccumBits   = 0;
 	const BYTE cDepthBits   = (BYTE)depthBufferBits;
-	const BYTE cStencilBits = 0;
+	const BYTE cStencilBits = (BYTE)stencilBufferBits;
 	const BYTE cAuxBuffers  = 0;
 
 	PIXELFORMATDESCRIPTOR pfd =
diff --git a/source/lib/sysdep/os/win/wsdl.h b/source/lib/sysdep/os/win/wsdl.h
index c46d6fd6fc..d3364ef6b4 100644
--- a/source/lib/sysdep/os/win/wsdl.h
+++ b/source/lib/sysdep/os/win/wsdl.h
@@ -57,6 +57,7 @@ LIB_API void SDL_Quit();
 typedef enum
 {
 	SDL_GL_DEPTH_SIZE,
+	SDL_GL_STENCIL_SIZE,
 	SDL_GL_DOUBLEBUFFER,	// ignored - always double buffered
 	SDL_GL_SWAP_CONTROL
 }
diff --git a/source/renderer/Renderer.cpp b/source/renderer/Renderer.cpp
index 7e921fd137..5a338091b9 100644
--- a/source/renderer/Renderer.cpp
+++ b/source/renderer/Renderer.cpp
@@ -1205,6 +1205,11 @@ void CRenderer::RenderSilhouettes()
 
 	float silhouetteAlpha = 0.75f;
 
+	// Silhouette blending requires an almost-universally-supported extension;
+	// fall back to non-blended if unavailable
+	if (!ogl_HaveExtension("GL_EXT_blend_color"))
+		silhouetteAlpha = 1.f;
+
 	glClear(GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
 
 	glColorMask(0, 0, 0, 0);
@@ -1245,10 +1250,10 @@ void CRenderer::RenderSilhouettes()
 		// a pixel once (using the colour of whatever model happens to be drawn first).
 		glEnable(GL_BLEND);
 		glBlendFunc(GL_CONSTANT_ALPHA, GL_ONE_MINUS_CONSTANT_ALPHA);
-		glBlendColor(0, 0, 0, silhouetteAlpha);
+		pglBlendColorEXT(0, 0, 0, silhouetteAlpha);
 
 		glEnable(GL_STENCIL_TEST);
-		glStencilFunc(GL_NOTEQUAL, 1, -1);
+		glStencilFunc(GL_NOTEQUAL, 1, (GLuint)-1);
 		glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
 	}
 
@@ -1265,11 +1270,17 @@ void CRenderer::RenderSilhouettes()
 
 	// Restore state
 	glDepthFunc(GL_LEQUAL);
-	glDepthMask(1);
-	glDisable(GL_BLEND);
-	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
-	glBlendColor(0, 0, 0, 0);
-	glDisable(GL_STENCIL_TEST);
+	if (silhouetteAlpha == 1.f)
+	{
+		glDepthMask(1);
+	}
+	else
+	{
+		glDisable(GL_BLEND);
+		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+		pglBlendColorEXT(0, 0, 0, 0);
+		glDisable(GL_STENCIL_TEST);
+	}
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/source/tools/atlas/AtlasUI/ScenarioEditor/ScenarioEditor.cpp b/source/tools/atlas/AtlasUI/ScenarioEditor/ScenarioEditor.cpp
index 23a7e941d4..97c2d0cac0 100644
--- a/source/tools/atlas/AtlasUI/ScenarioEditor/ScenarioEditor.cpp
+++ b/source/tools/atlas/AtlasUI/ScenarioEditor/ScenarioEditor.cpp
@@ -512,6 +512,7 @@ ScenarioEditor::ScenarioEditor(wxWindow* parent, ScriptInterface& scriptInterfac
 		WX_GL_RGBA,
 		WX_GL_DOUBLEBUFFER,
 		WX_GL_DEPTH_SIZE, 24, // TODO: wx documentation doesn't say 24 is valid
+		WX_GL_STENCIL_SIZE, 8,
 		WX_GL_BUFFER_SIZE, 24, // colour bits
 		WX_GL_MIN_ALPHA, 8, // alpha bits
 		0