diff --git a/desmume/src/OGLRender.cpp b/desmume/src/OGLRender.cpp
index 64aec648f..b78d309ec 100644
--- a/desmume/src/OGLRender.cpp
+++ b/desmume/src/OGLRender.cpp
@@ -4581,6 +4581,8 @@ Render3DError OpenGLRenderer_1_2::PostprocessFramebuffer()
 			
 			// Pass 3: Blended edge mark
 			glEnable(GL_BLEND);
+			glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_SRC_ALPHA, GL_DST_ALPHA);
+			glBlendEquationSeparate(GL_FUNC_ADD, GL_MAX);
 			glDisable(GL_STENCIL_TEST);
 			glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
 			glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
@@ -4595,6 +4597,8 @@ Render3DError OpenGLRenderer_1_2::PostprocessFramebuffer()
 			glUniform1i(OGLRef.uniformStateClearPolyID, this->_pendingRenderStates.clearPolyID);
 			glUniform1f(OGLRef.uniformStateClearDepth, this->_pendingRenderStates.clearDepth);
 			glEnable(GL_BLEND);
+			glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_SRC_ALPHA, GL_DST_ALPHA);
+			glBlendEquationSeparate(GL_FUNC_ADD, GL_MAX);
 			glDisable(GL_STENCIL_TEST);
 			glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
 			glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
diff --git a/desmume/src/OGLRender_3_2.cpp b/desmume/src/OGLRender_3_2.cpp
index 1ea560794..8fa9bb58a 100644
--- a/desmume/src/OGLRender_3_2.cpp
+++ b/desmume/src/OGLRender_3_2.cpp
@@ -3425,6 +3425,8 @@ Render3DError OpenGLRenderer_3_2::PostprocessFramebuffer()
 			
 			// Pass 3: Blended edge mark
 			glEnable(GL_BLEND);
+			glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_SRC_ALPHA, GL_DST_ALPHA);
+			glBlendEquationSeparate(GL_FUNC_ADD, GL_MAX);
 			glDisable(GL_STENCIL_TEST);
 			glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
 			glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
@@ -3433,6 +3435,8 @@ Render3DError OpenGLRenderer_3_2::PostprocessFramebuffer()
 		{
 			glUseProgram(pEdgeMarkID);
 			glEnable(GL_BLEND);
+			glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_SRC_ALPHA, GL_DST_ALPHA);
+			glBlendEquationSeparate(GL_FUNC_ADD, GL_MAX);
 			glDisable(GL_STENCIL_TEST);
 			glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
 			glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);