diff --git a/src/simulation/Simulation.cpp b/src/simulation/Simulation.cpp
index 1110e74156..0c5f4cf255 100644
--- a/src/simulation/Simulation.cpp
+++ b/src/simulation/Simulation.cpp
@@ -2406,9 +2406,9 @@ int Simulation::do_move(int i, int x, int y, float nxf, float nyf)
 		bool x_ok = (nx >= CELL && nx < XRES-CELL);
 		bool y_ok = (ny >= CELL && ny < YRES-CELL);
 		if (!x_ok)
-			nxf = remainder_p(nxf-CELL, XRES-CELL*2.0f)+CELL-.5f;
+			nxf = remainder_p(nxf-CELL+.5f, XRES-CELL*2.0f)+CELL-.5f;
 		if (!y_ok)
-			nyf = remainder_p(nyf-CELL, YRES-CELL*2.0f)+CELL-.5f;
+			nyf = remainder_p(nyf-CELL+.5f, YRES-CELL*2.0f)+CELL-.5f;
 		nx = (int)(nxf+0.5f);
 		ny = (int)(nyf+0.5f);
 
@@ -4079,9 +4079,9 @@ void Simulation::UpdateParticles(int start, int end)
 						bool x_ok = (fin_x >= CELL && fin_x < XRES-CELL);
 						bool y_ok = (fin_y >= CELL && fin_y < YRES-CELL);
 						if (!x_ok)
-							fin_xf = remainder_p(fin_xf-CELL, XRES-CELL*2.0f)+CELL-.5f;
+							fin_xf = remainder_p(fin_xf-CELL+.5f, XRES-CELL*2.0f)+CELL-.5f;
 						if (!y_ok)
-							fin_yf = remainder_p(fin_yf-CELL, YRES-CELL*2.0f)+CELL-.5f;
+							fin_yf = remainder_p(fin_yf-CELL+.5f, YRES-CELL*2.0f)+CELL-.5f;
 						fin_x = (int)(fin_xf+0.5f);
 						fin_y = (int)(fin_yf+0.5f);
 					}
@@ -4132,12 +4132,12 @@ void Simulation::UpdateParticles(int start, int end)
 					int oldnx = nx, oldny = ny;
 					if (!x_ok)
 					{
-						parts[i].x = remainder_p(parts[i].x-CELL, XRES-CELL*2.0f)+CELL-.5f;
+						parts[i].x = remainder_p(parts[i].x-CELL+.5f, XRES-CELL*2.0f)+CELL-.5f;
 						nx = (int)((float)parts[i].x+0.5f);
 					}
 					if (!y_ok)
 					{
-						parts[i].y = remainder_p(parts[i].y-CELL, YRES-CELL*2.0f)+CELL-.5f;
+						parts[i].y = remainder_p(parts[i].y-CELL+.5f, YRES-CELL*2.0f)+CELL-.5f;
 						ny = (int)((float)parts[i].y+0.5f);
 					}