diff --git a/nix/build-all.py b/nix/build-all.py
index 019da07fa8..768c2d171d 100644
--- a/nix/build-all.py
+++ b/nix/build-all.py
@@ -69,7 +69,7 @@ OCE_VERSION="0.18"
 PYTHON_VERSIONS=["2.7.16", "3.2.6", "3.3.6", "3.4.6", "3.5.3", "3.6.2"]
 # OCCT_VERSION="7.2.0"
 # OCCT_HASH="88af392"
-OCCT_VERSION="7.3.0"
+OCCT_VERSION="7.3.0p3"
 BOOST_VERSION="1.59.0"
 PCRE_VERSION="8.39"
 LIBXML_VERSION="2.9.3"
diff --git a/win/build-deps.cmd b/win/build-deps.cmd
index 175c00416b..2f30e1e55b 100644
--- a/win/build-deps.cmd
+++ b/win/build-deps.cmd
@@ -227,7 +227,7 @@ IF NOT %ERRORLEVEL%==0 GOTO :Error
 
 if %IFCOS_USE_OCCT%==FALSE goto :OCE
 :OCCT
-set OCCT_VERSION=7.3.0
+set OCCT_VERSION=7.3.0p3
 SET OCCT_VER=V%OCCT_VERSION:.=_%
 
 set OCC_INCLUDE_DIR=%INSTALL_DIR%\opencascade-%OCCT_VERSION%\inc>>"%~dp0\BuildDepsCache-%TARGET_ARCH%.txt"
diff --git a/win/patches/V7_3_0p3.patch b/win/patches/V7_3_0p3.patch
new file mode 100644
index 0000000000..efc9154b75
--- /dev/null
+++ b/win/patches/V7_3_0p3.patch
@@ -0,0 +1,77 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index fca978164..dda41e2c6 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -426,6 +426,9 @@ endforeach()
+ if (NOT BUILD_SHARED_LIBS)
+   list (REMOVE_ITEM BUILD_TOOLKITS DRAWEXE)
+   message (STATUS "Info: DRAWEXE is not included due to ${BUILD_LIBRARY_TYPE} build library type")
++  # IfcOpenShell begin
++  add_definitions(-DHAVE_NO_DLL)
++  # IfcOpenShell end
+ endif()
+ 
+ # accumulate all used toolkits
+diff --git a/adm/cmake/occt_defs_flags.cmake b/adm/cmake/occt_defs_flags.cmake
+index 09da18d38..a07b9cf74 100644
+--- a/adm/cmake/occt_defs_flags.cmake
++++ b/adm/cmake/occt_defs_flags.cmake
+@@ -138,5 +138,21 @@ if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR MINGW)
+   set (CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -s")
+ endif()
+ 
+-set (CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -DNo_Exception")
+-set (CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -DNo_Exception")
++# IfcOpenShell begin
++# https://salsa.debian.org/science-team/opencascade/blob/739e7e9c4fbe575165eb3ff0251774bfad27139e/debian/patches/enable-exception-handling.patch
++# set (CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -DNo_Exception")
++# set (CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -DNo_Exception")
++
++if (MSVC)
++    foreach(flag CMAKE_CXX_FLAGS CMAKE_CXX_FLAGS_DEBUG CMAKE_CXX_FLAGS_RELEASE CMAKE_CXX_FLAGS_MINSIZEREL
++            CMAKE_CXX_FLAGS_RELWITHDEBINFO CMAKE_C_FLAGS CMAKE_C_FLAGS_DEBUG CMAKE_C_FLAGS_RELEASE
++            CMAKE_C_FLAGS_MINSIZEREL CMAKE_C_FLAGS_RELWITHDEBINFO)
++        if (${flag} MATCHES "/MD")
++            string(REGEX REPLACE "/MD" "/MT" ${flag} "${${flag}}")
++        endif()
++        if (${flag} MATCHES "/MDd")
++            string(REGEX REPLACE "/MDd" "/MTd" ${flag} "${${flag}}")
++        endif()
++    endforeach()
++endif()
++# IfcOpenShell end
+diff --git a/adm/cmake/occt_toolkit.cmake b/adm/cmake/occt_toolkit.cmake
+index f59b1639d..aee227516 100644
+--- a/adm/cmake/occt_toolkit.cmake
++++ b/adm/cmake/occt_toolkit.cmake
+@@ -208,11 +208,26 @@ if (EXECUTABLE_PROJECT)
+ else()
+   add_library (${PROJECT_NAME} ${USED_SRCFILES} ${USED_INCFILES} ${USED_RCFILE} ${RESOURCE_FILES} ${${PROJECT_NAME}_MOC_FILES})
+ 
+-  if (MSVC)
+-    install (FILES  ${CMAKE_BINARY_DIR}/${OS_WITH_BIT}/${COMPILER}/bin\${OCCT_INSTALL_BIN_LETTER}/${PROJECT_NAME}.pdb
+-             CONFIGURATIONS Debug RelWithDebInfo
+-             DESTINATION "${INSTALL_DIR_BIN}\${OCCT_INSTALL_BIN_LETTER}")
++  # IfcOpenShell begin
++  if (BUILD_SHARED_LIBS)
++    if (MSVC)
++      install (FILES  ${CMAKE_BINARY_DIR}/${OS_WITH_BIT}/${COMPILER}/bin\${OCCT_INSTALL_BIN_LETTER}/${PROJECT_NAME}.pdb
++               CONFIGURATIONS Debug RelWithDebInfo
++               DESTINATION "${INSTALL_DIR_BIN}\${OCCT_INSTALL_BIN_LETTER}")
++    endif()
++  else()
++    if (MSVC)
++      set_target_properties (${PROJECT_NAME} PROPERTIES
++        COMPILE_PDB_NAME ${PROJECT_NAME}
++        COMPILE_PDB_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/${OS_WITH_BIT}/${COMPILER}/pdb/
++      )
++
++      install (FILES  ${CMAKE_BINARY_DIR}/${OS_WITH_BIT}/${COMPILER}/pdb/\${CMAKE_INSTALL_CONFIG_NAME}/${PROJECT_NAME}.pdb
++               CONFIGURATIONS Debug RelWithDebInfo
++               DESTINATION "${INSTALL_DIR_LIB}\${OCCT_INSTALL_BIN_LETTER}")
++    endif()
+   endif()
++  # IfcOpenShell end
+ 
+   if (BUILD_SHARED_LIBS AND NOT "${BUILD_SHARED_LIBRARY_NAME_POSTFIX}" STREQUAL "")
+     set (CMAKE_SHARED_LIBRARY_SUFFIX_DEFAULT ${CMAKE_SHARED_LIBRARY_SUFFIX})