diff --git a/qglview/gltypes.h b/qglview/gltypes.h
index 27658ec..0f79ddd 100644
--- a/qglview/gltypes.h
+++ b/qglview/gltypes.h
@@ -158,7 +158,7 @@ inline void glSetCapEnabled(GLenum cap, bool on = true) {if (on) glEnable(cap);
 inline void glSetLightEnabled(bool on) {if (on) glEnable(GL_LIGHTING); else glDisable(GL_LIGHTING);}
 inline void glSetFogEnabled(bool on) {if (on) glEnable(GL_FOG); else glDisable(GL_FOG);}
 inline void glSetPolygonMode(GLenum mode) {glPolygonMode(GL_FRONT_AND_BACK, mode);}
-void glDrawQuad(QOpenGLShaderProgram * prog = nullptr, QVector4D * corner_dirs = nullptr, GLfloat x = -1.f, GLfloat y = -1.f, GLfloat w = 2.f, GLfloat h = 2.f);
+void glDrawQuad(QOpenGLShaderProgram * prog = 0, QVector4D * corner_dirs = 0, GLfloat x = -1.f, GLfloat y = -1.f, GLfloat w = 2.f, GLfloat h = 2.f);
 QMatrix4x4 getGLMatrix(GLenum matrix);
 void setGLMatrix(QMatrix4x4 matrix);
 inline void deleteGLTexture(GLuint & tex) {if (tex != 0) glDeleteTextures(1, &tex); tex = 0;}