diff --git a/src/g_demo.cpp b/src/g_demo.cpp
index 61fba51f6..feb35c5c8 100644
--- a/src/g_demo.cpp
+++ b/src/g_demo.cpp
@@ -169,8 +169,11 @@ demoghost *ghosts = NULL;
 //   - Slope physics changed with a scaling fix
 // - 0x000C (Ring Racers v2.2)
 // - 0x000D (Ring Racers v2.3)
+// - 0x000E (Ring Racers v2.4 in-dev before DYNSLOPE thinker change)
+// - 0x000F (Ring Racers v2.4)
 
-#define DEMOVERSION 0x000E
+#define MINDEMOVERSION 0x000E
+#define DEMOVERSION 0x000F
 
 boolean G_CompatLevel(UINT16 level)
 {
@@ -2440,7 +2443,7 @@ UINT8 G_CmpDemoTime(char *oldname, char *newname)
 	c = READUINT8(p); // SUBVERSION
 	I_Assert(c == SUBVERSION);
 	s = READUINT16(p);
-	I_Assert(s == DEMOVERSION);
+	I_Assert(s >= MINDEMOVERSION && s <= DEMOVERSION);
 	p += 64; // full demo title
 	p += 16; // demo checksum
 	I_Assert(!memcmp(p, "PLAY", 4));
@@ -2488,6 +2491,8 @@ UINT8 G_CmpDemoTime(char *oldname, char *newname)
 	oldversion = READUINT16(p);
 	switch(oldversion) // demoversion
 	{
+	case 0x000E:
+		/* fallthru */
 	case DEMOVERSION: // latest always supported
 		break;
 	// too old, cannot support.
@@ -2636,6 +2641,8 @@ void G_LoadDemoInfo(menudemo_t *pdemo, boolean allownonmultiplayer)
 
 	switch(pdemoversion)
 	{
+	case 0x000E:
+		/* fallthru */
 	case DEMOVERSION: // latest always supported
 		if (P_SaveBufferRemaining(&info) < 64)
 		{
@@ -3033,6 +3040,8 @@ void G_DoPlayDemoEx(const char *defdemoname, lumpnum_t deflumpnum)
 	demo.version = READUINT16(demobuf.p);
 	switch(demo.version)
 	{
+	case 0x000E:
+		/* fallthru */
 	case DEMOVERSION: // latest always supported
 		break;
 	// too old, cannot support.
@@ -3521,6 +3530,8 @@ void G_AddGhost(savebuffer_t *buffer, const char *defdemoname)
 	ghostversion = READUINT16(p);
 	switch(ghostversion)
 	{
+	case 0x000E:
+		/* fallthru */
 	case DEMOVERSION: // latest always supported
 		break;
 	// too old, cannot support.
@@ -3805,6 +3816,8 @@ staffbrief_t *G_GetStaffGhostBrief(UINT8 *buffer)
 	ghostversion = READUINT16(p);
 	switch(ghostversion)
 	{
+		case 0x000E:
+			/* fallthru */
 		case DEMOVERSION: // latest always supported
 			break;
 
diff --git a/src/p_slopes.c b/src/p_slopes.c
index 247f34557..b80c784c5 100644
--- a/src/p_slopes.c
+++ b/src/p_slopes.c
@@ -13,6 +13,7 @@
 
 #include "d_think.h"
 #include "doomdef.h"
+#include "g_demo.h"
 #include "r_defs.h"
 #include "r_state.h"
 #include "m_bbox.h"
@@ -308,7 +309,7 @@ static inline void P_AddDynLineSlopeThinker (pslope_t* slope, dynplanetype_t typ
 	th->sourceline = sourceline;
 	th->extent = extent;
 	// Handle old demos as well.
-	P_AddThinker(/*G_CompatLevel(0x000D) ? THINK_DYNSLOPEDEMO :*/ THINK_DYNSLOPE, &th->thinker);
+	P_AddThinker(G_CompatLevel(0x000E) ? THINK_DYNSLOPEDEMO : THINK_DYNSLOPE, &th->thinker);
 
 	// interpolation
 	R_CreateInterpolator_DynSlope(&th->thinker, slope);
@@ -339,7 +340,7 @@ static inline void P_AddDynVertexSlopeThinker (pslope_t* slope, const INT16 tags
 			th->relative |= 1<<i;
 	}
 	// Handle old demos as well.
-	P_AddThinker(/*G_CompatLevel(0x000D) ? THINK_DYNSLOPEDEMO :*/ THINK_DYNSLOPE, &th->thinker);
+	P_AddThinker(G_CompatLevel(0x000E) ? THINK_DYNSLOPEDEMO : THINK_DYNSLOPE, &th->thinker);
 }
 
 /// Create a new slope and add it to the slope list.