diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index 44f80a49c..39c76062e 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,3 +1,7 @@
+October 19, 2009  (Changes by Graf Zahl)
+- fixed: Setting the first state's duration of a fast projectile to 0 caused
+  an underflow and blocked all further state changes.
+
 October 18, 2009  (Changes by Graf Zahl)
 - fixed: FMultiPatchTexture::MakeTexture was missing a range check for the
   special colormap index.
diff --git a/src/g_shared/a_fastprojectile.cpp b/src/g_shared/a_fastprojectile.cpp
index d3924a17e..fe97e6a53 100644
--- a/src/g_shared/a_fastprojectile.cpp
+++ b/src/g_shared/a_fastprojectile.cpp
@@ -99,7 +99,7 @@ void AFastProjectile::Tick ()
 	// Advance the state
 	if (tics != -1)
 	{
-		tics--;
+		if (tics > 0) tics--;
 		while (!tics)
 		{
 			if (!SetState (state->GetNextState ()))