diff --git a/techlibs/common/simlib.v b/techlibs/common/simlib.v
index f07b3f2210e..103115e26dc 100644
--- a/techlibs/common/simlib.v
+++ b/techlibs/common/simlib.v
@@ -1234,22 +1234,22 @@ parameter C_SIGNED = 1'bx;
 
 function integer sum_widths1;
 	input [(16*NPRODUCTS)-1:0] widths;
-	int i;
+	integer i;
 	sum_widths1 = 0;
 	begin
 		for (i = 0; i < NPRODUCTS; i++) begin
-			sum_widths1 += widths[16*i+:16];
+			sum_widths1 = sum_widths1 + widths[16*i+:16];
 		end
 	end
 endfunction
 
 function integer sum_widths2;
 	input [(16*NADDENDS)-1:0] widths;
-	int i;
+	integer i;
 	sum_widths2 = 0;
 	begin
 		for (i = 0; i < NADDENDS; i++) begin
-			sum_widths2 += widths[16*i+:16];
+			sum_widths2 = sum_widths2 + widths[16*i+:16];
 		end
 	end
 endfunction
@@ -1286,15 +1286,15 @@ always @* begin
 				oper_b[j] = oper_b[j - 1];
 		end
 
-		product = A[ai +: aw] * B[bi +: bw];
+		product = oper_a * oper_b;
 
 		if (PRODUCT_NEGATED[i])
 			Y = Y - product;
 		else
 			Y = Y + product;
 
-		ai += aw;
-		bi += bw;
+		ai = ai + aw;
+		bi = bi + bw;
 	end
 
 	ci = 0;
@@ -1315,7 +1315,7 @@ always @* begin
 		else
 			Y = Y + addend;
 
-		ci += cw;
+		ci = ci + cw;
 	end
 end