diff --git a/src/hardware/hw_drv.h b/src/hardware/hw_drv.h
index e0c2f327..7672f47c 100644
--- a/src/hardware/hw_drv.h
+++ b/src/hardware/hw_drv.h
@@ -66,7 +66,7 @@ EXPORT void HWRAPI(SetSpecialState) (hwdspecialstate_t IdState, INT32 Value);
 
 //Hurdler: added for new development
 EXPORT void HWRAPI(DrawMD2) (INT32 *gl_cmd_buffer, md2_frame_t *frame, FTransform *pos, float scale);
-EXPORT void HWRAPI(DrawMD2i) (INT32 *gl_cmd_buffer, md2_frame_t *frame, UINT32 duration, UINT32 tics, md2_frame_t *nextframe, FTransform *pos, float scale, UINT8 flipped, UINT8 *color);
+EXPORT void HWRAPI(DrawMD2i) (INT32 *gl_cmd_buffer, md2_frame_t *frame, INT32 duration, INT32 tics, md2_frame_t *nextframe, FTransform *pos, float scale, UINT8 flipped, UINT8 *color);
 EXPORT void HWRAPI(SetTransform) (FTransform *ptransform);
 EXPORT INT32 HWRAPI(GetTextureUsed) (void);
 EXPORT INT32 HWRAPI(GetRenderVersion) (void);
diff --git a/src/hardware/hw_md2.c b/src/hardware/hw_md2.c
index 4ec2e346..f59c1d4f 100644
--- a/src/hardware/hw_md2.c
+++ b/src/hardware/hw_md2.c
@@ -1252,8 +1252,8 @@ void HWR_DrawMD2(gr_vissprite_t *spr)
 	{
 		GLPatch_t *gpatch;
 		INT32 *buff;
-		UINT32 durs = spr->mobj->state->tics;
-		UINT32 tics = spr->mobj->tics;
+		INT32 durs = spr->mobj->state->tics;
+		INT32 tics = spr->mobj->tics;
 		md2_frame_t *curr, *next = NULL;
 		const UINT8 flip = (UINT8)((spr->mobj->eflags & MFE_VERTICALFLIP) == MFE_VERTICALFLIP);
 		spritedef_t *sprdef;
diff --git a/src/hardware/r_opengl/r_opengl.c b/src/hardware/r_opengl/r_opengl.c
index e6ff83e8..205b399b 100644
--- a/src/hardware/r_opengl/r_opengl.c
+++ b/src/hardware/r_opengl/r_opengl.c
@@ -1819,15 +1819,14 @@ EXPORT void HWRAPI(SetSpecialState) (hwdspecialstate_t IdState, INT32 Value)
 	}
 }
 
-static  void DrawMD2Ex(INT32 *gl_cmd_buffer, md2_frame_t *frame, UINT32 duration, UINT32 tics, md2_frame_t *nextframe, FTransform *pos, float scale, UINT8 flipped, UINT8 *color)
+static  void DrawMD2Ex(INT32 *gl_cmd_buffer, md2_frame_t *frame, INT32 duration, INT32 tics, md2_frame_t *nextframe, FTransform *pos, float scale, UINT8 flipped, UINT8 *color)
 {
 	INT32     val, count, pindex;
 	GLfloat s, t;
 	GLfloat ambient[4];
 	GLfloat diffuse[4];
 
-	float pol;
-	UINT32 newtime;
+	float pol = 0.0f;
 	float scalex = scale, scaley = scale, scalez = scale;
 
 	// Because Otherwise, scaling the screen negatively vertically breaks the lighting
@@ -1835,18 +1834,18 @@ static  void DrawMD2Ex(INT32 *gl_cmd_buffer, md2_frame_t *frame, UINT32 duration
 	GLfloat LightPos[] = {0.0f, 1.0f, 0.0f, 0.0f};
 #endif
 
-	if (duration == 0)
-		duration = 1;
+	if (duration != 0 && duration != -1 && tics != -1) // don't interpolate if instantaneous or infinite in length
+	{
+		UINT32 newtime = (duration - tics); // + 1;
 
-	newtime = (duration - tics) + 1;
+		pol = (newtime)/(float)duration;
 
-	pol = (newtime)/(float)duration;
+		if (pol > 1.0f)
+			pol = 1.0f;
 
-	if (pol > 1.0f)
-		pol = 1.0f;
-
-	if (pol < 0.0f)
-		pol = 0.0f;
+		if (pol < 0.0f)
+			pol = 0.0f;
+	}
 
 	if (color)
 	{
@@ -1940,7 +1939,7 @@ static  void DrawMD2Ex(INT32 *gl_cmd_buffer, md2_frame_t *frame, UINT32 duration
 
 			pglTexCoord2f(s, t);
 
-			if (!nextframe)
+			if (!nextframe || pol == 0.0f)
 			{
 				pglNormal3f(frame->vertices[pindex].normal[0],
 				            frame->vertices[pindex].normal[1],
@@ -1990,7 +1989,7 @@ static  void DrawMD2Ex(INT32 *gl_cmd_buffer, md2_frame_t *frame, UINT32 duration
 // -----------------+
 // HWRAPI DrawMD2   : Draw an MD2 model with glcommands
 // -----------------+
-EXPORT void HWRAPI(DrawMD2i) (INT32 *gl_cmd_buffer, md2_frame_t *frame, UINT32 duration, UINT32 tics, md2_frame_t *nextframe, FTransform *pos, float scale, UINT8 flipped, UINT8 *color)
+EXPORT void HWRAPI(DrawMD2i) (INT32 *gl_cmd_buffer, md2_frame_t *frame, INT32 duration, INT32 tics, md2_frame_t *nextframe, FTransform *pos, float scale, UINT8 flipped, UINT8 *color)
 {
 	DrawMD2Ex(gl_cmd_buffer, frame, duration, tics,  nextframe, pos, scale, flipped, color);
 }