diff --git a/src/elements/neut.c b/src/elements/neut.c
index 0d12a6ddc..85a0be25e 100644
--- a/src/elements/neut.c
+++ b/src/elements/neut.c
@@ -21,6 +21,7 @@ int create_n_parts(int n, int x, int y, float vx, float vy, float temp, int t)//
 			return -1;
 		i = pfree;
 		pfree = parts[i].life;
+		if (i>parts_lastActiveIndex) parts_lastActiveIndex = i;
 
 		parts[i].x = (float)x;
 		parts[i].y = (float)y;
diff --git a/src/powder.c b/src/powder.c
index 4068e3cda..88cb71351 100644
--- a/src/powder.c
+++ b/src/powder.c
@@ -1026,6 +1026,7 @@ static void create_gain_photon(int pp)//photons from PHOT going through GLOW
 		return;
 
 	pfree = parts[i].life;
+	if (i>parts_lastActiveIndex) parts_lastActiveIndex = i;
 
 	parts[i].type = PT_PHOT;
 	parts[i].life = 680;
@@ -1062,6 +1063,7 @@ static void create_cherenkov_photon(int pp)//photons from NEUT going through GLA
 		return;
 
 	pfree = parts[i].life;
+	if (i>parts_lastActiveIndex) parts_lastActiveIndex = i;
 
 	lr = rand() % 2;