diff --git a/CMakeLists.txt b/CMakeLists.txt
index e1b1911..a1ee634 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,7 +6,11 @@ project(openFPGALoader VERSION "0.5.0" LANGUAGES CXX)
 add_definitions(-DVERSION=\"v${PROJECT_VERSION}\")
 
 option(BUILD_STATIC "Whether or not to build with static libraries" OFF)
-option(ENABLE_UDEV "use udev to search JTAG adapter from /dev/xx" ON)
+if (${CMAKE_SYSTEM_NAME} MATCHES "Windows")
+ set(ENABLE_UDEV OFF)
+else()
+ option(ENABLE_UDEV "use udev to search JTAG adapter from /dev/xx" ON)
+endif()
 option(ENABLE_CMSISDAP "enable cmsis DAP interface (requires hidapi)" ON)
 option(USE_PKGCONFIG "Use pkgconfig to find libraries" ON)
 option(LINK_CMAKE_THREADS "Use CMake find_package to link the threading library" OFF)
diff --git a/src/xilinx.cpp b/src/xilinx.cpp
index a83ec08..1f9ebf3 100644
--- a/src/xilinx.cpp
+++ b/src/xilinx.cpp
@@ -448,7 +448,7 @@ void Xilinx::flow_enable()
 void Xilinx::flow_disable()
 {
 	_jtag->shiftIR(XC95_ISC_DISABLE, 8);
-	usleep(100);
+	_jtag->toggleClk((_jtag->getClkFreq() * 100) / 1000000);
 	_jtag->shiftIR(BYPASS, 8);
 	_jtag->toggleClk(1);
 }
@@ -461,7 +461,7 @@ bool Xilinx::flow_erase()
 
 	_jtag->shiftIR(XC95_ISC_ERASE, 8);
 	_jtag->shiftDR(xfer_buf, NULL, 18);
-	_jtag->toggleClk(2000000);
+	_jtag->toggleClk((_jtag->getClkFreq() * 400) / 1000);
 	_jtag->shiftDR(NULL, xfer_buf, 18);
 	if ((xfer_buf[0] & 0x03) != 0x01) {
 		printError("FAIL");
@@ -500,10 +500,6 @@ bool Xilinx::flow_program()
 	}
 	printSuccess("DONE");
 
-	/* limit JTAG clock frequency to 1MHz */
-	if (_jtag->getClkFreq() > 1e6)
-		_jtag->setClkFreq(1e6);
-
 	/* enable ISC */
 	flow_enable();
 
@@ -545,7 +541,7 @@ bool Xilinx::flow_program()
 					_jtag->shiftIR(XC95_ISC_PROGRAM, 8);
 					_jtag->shiftDR(&mode, NULL, 2, Jtag::SHIFT_DR);
 					_jtag->shiftDR(wr_buf, NULL, 8 * (_xc95_line_len + 2));
-					_jtag->toggleClk(50000);
+					_jtag->toggleClk((_jtag->getClkFreq() * 50) / 1000);
 					_jtag->shiftDR(NULL, rd_buf, 8 * (_xc95_line_len + 2) + 2);
 					if ((rd_buf[0] & 0x03) == 0x01)
 						break;