diff --git a/specs/udmf_zdoom.txt b/specs/udmf_zdoom.txt
index d56b8ed0b..9d7bb3caf 100644
--- a/specs/udmf_zdoom.txt
+++ b/specs/udmf_zdoom.txt
@@ -199,6 +199,12 @@ Note: All <bool> fields default to false unless mentioned otherwise.
       conversation = <int>		// Assigns a conversation dialogue to this thing.
                                 // Parameter is the conversation ID, 0 meaning none.
       countsecret = <bool>;     // Picking up this actor counts as a secret.
+      arg0str = <string>;       // Alternate string-based version of arg0
+
+      * Note about arg0str
+
+      For things with ACS specials (80-86 and 226), if arg0str is present and non-null, it
+      will be used as the name of the script to execute, and arg0 will be ignored.
    }
 
 
@@ -316,6 +322,9 @@ Standardized whitespace.
 1.19 24.02.2012
 Added back locknumber property.
 
+1.20 25.02.2012
+Added arg0str thing property.
+
 ===============================================================================
 EOF
 ===============================================================================
diff --git a/src/p_udmf.cpp b/src/p_udmf.cpp
index ab0a3e8af..cf130f267 100644
--- a/src/p_udmf.cpp
+++ b/src/p_udmf.cpp
@@ -466,6 +466,8 @@ public:
 
 	void ParseThing(FMapThing *th)
 	{
+		FString arg0str;
+
 		memset(th, 0, sizeof(*th));
 		sc.MustGetToken('{');
 		while (!sc.CheckToken('}'))
@@ -516,6 +518,11 @@ public:
 				th->args[int(key)-int(NAME_Arg0)] = CheckInt(key);
 				break;
 
+			case NAME_Arg0Str:
+				CHECK_N(Zd);
+				arg0str = CheckString(key);
+				break;
+
 			case NAME_Skill1:
 			case NAME_Skill2:
 			case NAME_Skill3:
@@ -616,6 +623,10 @@ public:
 				break;
 			}
 		}
+		if (arg0str.IsNotEmpty() && P_IsACSSpecial(th->special))
+		{
+			th->args[0] = -FName(arg0str);
+		}
 		// Thing specials are only valid in namespaces with Hexen-type specials
 		// and in ZDoomTranslated - which will use the translator on them.
 		if (namespc == NAME_ZDoomTranslated)