diff --git a/source/duke3d/src/gamedef.cpp b/source/duke3d/src/gamedef.cpp
index 965d08e82..39a594fe0 100644
--- a/source/duke3d/src/gamedef.cpp
+++ b/source/duke3d/src/gamedef.cpp
@@ -573,6 +573,7 @@ const char *keyw[] =
     "ifplaybackon",             // 399
     "divscale",                 // 400
     "scalevar",                 // 401
+    "undefinegamefunc",         // 402
     "<null>"
 };
 #endif
@@ -5419,6 +5420,25 @@ repeatcase:
 
             continue;
 
+        case CON_UNDEFINEGAMEFUNC:
+            g_scriptPtr--;
+            C_GetNextValue(LABEL_DEFINE);
+            g_scriptPtr--;
+            j = *g_scriptPtr;
+
+            if (EDUKE32_PREDICT_FALSE((unsigned)j > NUMGAMEFUNCTIONS-1))
+            {
+                initprintf("%s:%d: error: function number exceeds number of game functions.\n",
+                    g_scriptFileName,g_lineNumber);
+                g_errorCnt++;
+                C_NextLine();
+                continue;
+            }
+
+            gamefunctions[j][0] = '\0';
+
+            continue;
+
         case CON_DEFINESKILLNAME:
             g_scriptPtr--;
 
diff --git a/source/duke3d/src/gamedef.h b/source/duke3d/src/gamedef.h
index 09d513402..97c07d3cb 100644
--- a/source/duke3d/src/gamedef.h
+++ b/source/duke3d/src/gamedef.h
@@ -1131,6 +1131,7 @@ enum ScriptKeywords_t
     CON_IFPLAYBACKON,       // 399
     CON_DIVSCALE,           // 400
     CON_SCALEVAR,           // 401
+    CON_UNDEFINEGAMEFUNC,   // 402
     CON_END
 };
 // KEEPINSYNC with the keyword list in lunatic/con_lang.lua