diff --git a/plugins/GSdx/GSRendererDX.cpp b/plugins/GSdx/GSRendererDX.cpp
index 140bfa96f5..8f75272880 100644
--- a/plugins/GSdx/GSRendererDX.cpp
+++ b/plugins/GSdx/GSRendererDX.cpp
@@ -159,7 +159,7 @@ void GSRendererDX::EmulateZbuffer()
 
 	GSVertex* v = &m_vertex.buff[0];
 	// Minor optimization of a corner case (it allow to better emulate some alpha test effects)
-	if (om_dssel.ztst == ZTST_GEQUAL && (m_vt.m_eq.xyzf & 0x8) && v[0].XYZ.Z == max_z) {
+	if (om_dssel.ztst == ZTST_GEQUAL && (m_vt.m_eq.xyzf & 0x4) && v[0].XYZ.Z == max_z) {
 #ifdef _DEBUG
 		fprintf(stdout, "Optimize Z test GEQUAL to ALWAYS (%s)\n", psm_str(m_context->ZBUF.PSM));
 #endif
diff --git a/plugins/GSdx/GSRendererOGL.cpp b/plugins/GSdx/GSRendererOGL.cpp
index 5c82b187dd..935f93789d 100644
--- a/plugins/GSdx/GSRendererOGL.cpp
+++ b/plugins/GSdx/GSRendererOGL.cpp
@@ -253,7 +253,7 @@ void GSRendererOGL::EmulateZbuffer()
 
 	GSVertex* v = &m_vertex.buff[0];
 	// Minor optimization of a corner case (it allow to better emulate some alpha test effects)
-	if (m_om_dssel.ztst == ZTST_GEQUAL && (m_vt.m_eq.xyzf & 0x8) && v[0].XYZ.Z == max_z) {
+	if (m_om_dssel.ztst == ZTST_GEQUAL && (m_vt.m_eq.xyzf & 0x4) && v[0].XYZ.Z == max_z) {
 		GL_INS("Optimize Z test GEQUAL to ALWAYS (%s)", psm_str(m_context->ZBUF.PSM));
 		m_om_dssel.ztst = ZTST_ALWAYS;
 	}