diff --git a/frontends/verilog/preproc.cc b/frontends/verilog/preproc.cc
index e17531be2..023c4dbcc 100644
--- a/frontends/verilog/preproc.cc
+++ b/frontends/verilog/preproc.cc
@@ -206,6 +206,7 @@ std::string frontend_verilog_preproc(FILE *f, std::string filename, const std::m
 {
 	std::map<std::string, std::string> defines_map(pre_defines_map);
 	int ifdef_fail_level = 0;
+	bool in_elseif = false;
 
 	output_code.clear();
 	input_buffer.clear();
@@ -222,17 +223,29 @@ std::string frontend_verilog_preproc(FILE *f, std::string filename, const std::m
 		if (tok == "`endif") {
 			if (ifdef_fail_level > 0)
 				ifdef_fail_level--;
+			if (ifdef_fail_level == 0)
+				in_elseif = false;
 			continue;
 		}
 
 		if (tok == "`else") {
 			if (ifdef_fail_level == 0)
 				ifdef_fail_level = 1;
-			else if (ifdef_fail_level == 1)
+			else if (ifdef_fail_level == 1 && !in_elseif)
 				ifdef_fail_level = 0;
 			continue;
 		}
 
+		if (tok == "`elsif") {
+			skip_spaces();
+			std::string name = next_token(true);
+			if (ifdef_fail_level == 0)
+				ifdef_fail_level = 1, in_elseif = true;
+			else if (ifdef_fail_level == 1 && defines_map.count(name) != 0)
+				ifdef_fail_level = 0, in_elseif = true;
+			continue;
+		}
+
 		if (tok == "`ifdef") {
 			skip_spaces();
 			std::string name = next_token(true);
diff --git a/tests/simple/macros.v b/tests/simple/macros.v
index e2025717f..cda46cb48 100644
--- a/tests/simple/macros.v
+++ b/tests/simple/macros.v
@@ -1,9 +1,237 @@
-module test(a, y);
+
+module test_def(a, y);
+
 `define MSB_LSB_SEP :
 `define get_msb(off, len) ((off)+(len)-1)
 `define get_lsb(off, len) (off)
 `define sel_bits(offset, len) `get_msb(offset, len) `MSB_LSB_SEP `get_lsb(offset, len)
+
 input [31:0] a;
 output [7:0] y;
+
 assign y = a[`sel_bits(16, 8)];
+
+endmodule
+
+// ---------------------------------------------------
+
+module test_ifdef(a, y);
+
+input [2:0] a;
+output reg [31:0] y;
+
+always @* begin
+	y = 0;
+
+	`undef X
+	`ifdef X
+		y = y + 42;
+	`else
+		`undef  A
+		`undef  B
+		`ifdef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`undef  A
+		`define B
+		`ifdef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`undef  B
+		`ifdef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`define B
+		`ifdef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		// ------------------------------------
+		`undef  A
+		`undef  B
+		`ifndef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`undef  A
+		`define B
+		`ifndef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`undef  B
+		`ifndef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`define B
+		`ifndef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		// ------------------------------------
+		`undef A
+		`ifdef A
+			y = (y << 1) | a[0];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`ifdef A
+			y = (y << 1) | a[0];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		// ------------------------------------
+		`undef A
+		`ifndef A
+			y = (y << 1) | a[0];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`ifndef A
+			y = (y << 1) | a[0];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+	`endif
+
+	`define X
+	`ifdef X
+		`undef  A
+		`undef  B
+		`ifdef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`undef  A
+		`define B
+		`ifdef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`undef  B
+		`ifdef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`define B
+		`ifdef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		// ------------------------------------
+		`undef  A
+		`undef  B
+		`ifndef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`undef  A
+		`define B
+		`ifndef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`undef  B
+		`ifndef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`define B
+		`ifndef A
+			y = (y << 1) | a[0];
+		`elsif B
+			y = (y << 1) | a[1];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		// ------------------------------------
+		`undef A
+		`ifdef A
+			y = (y << 1) | a[0];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`ifdef A
+			y = (y << 1) | a[0];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		// ------------------------------------
+		`undef A
+		`ifndef A
+			y = (y << 1) | a[0];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+		`define A
+		`ifndef A
+			y = (y << 1) | a[0];
+		`else
+			y = (y << 1) | a[2];
+		`endif
+	`else
+		y = y + 42;
+	`endif
+end
+
 endmodule