diff --git a/ginac.cmake-find-python.patch b/ginac.cmake-find-python.patch
new file mode 100644
index 0000000..fafcba7
--- /dev/null
+++ b/ginac.cmake-find-python.patch
@@ -0,0 +1,77 @@
+commit 8ae03bd2b1beca9210445aac33e0dcc8e0e90f0b
+Author: Till Hofmann <thofmann@fedoraproject.org>
+Date:   Sat Jul 14 13:00:45 2018 +0200
+
+    cmake: search for python interpreter and use the found interpreter
+    
+    Instead of just calling 'python', find the correct python interpreter
+    with find_package and use that interpreter when calling python.
+    
+    This avoids a bug on systems that do not provide an unversioned python
+    (i.e., that use 'python2' instead of 'python'). This should also avoid
+    using the python3 interpeter on accident.
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index cdb18f09..33e3f18c 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -17,6 +17,8 @@ string(REGEX REPLACE "^.*GINAC_LT_REVISION[ \t]+([0-9]+).*" "\\1" ginac_lt_revis
+ math(EXPR ginaclib_soversion "${ginac_lt_current} - ${ginac_lt_age}")
+ set(ginaclib_version ${ginaclib_soversion}.${ginac_lt_age}.${ginac_lt_revision})
+ 
++find_package(PythonInterp 2 EXACT REQUIRED)
++
+ # make check
+ enable_testing()
+ add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND})
+diff --git a/doc/CMakeLists.txt b/doc/CMakeLists.txt
+index e1416d31..7a226a26 100644
+--- a/doc/CMakeLists.txt
++++ b/doc/CMakeLists.txt
+@@ -45,7 +45,7 @@ macro(pdflatex_process texfile)
+ 	add_custom_command(
+ 		OUTPUT ${_ind}
+ 		COMMAND ${MAKEINDEX_COMPILER} ${_idx}
+-		COMMAND python ${_fixupind} ${_idx}
++		COMMAND ${PYTHON_EXECUTABLE} ${_fixupind} ${_idx}
+ 		WORKING_DIRECTORY ${_dirname}
+ 		DEPENDS ${texfile} ${_idx}
+ 		COMMENT "MAKEINDEX ${_basename}.idx")
+diff --git a/ginac/CMakeLists.txt b/ginac/CMakeLists.txt
+index 27f4db8d..d3d344c1 100644
+--- a/ginac/CMakeLists.txt
++++ b/ginac/CMakeLists.txt
+@@ -168,11 +168,11 @@ install(FILES ${ginaclib_public_headers} DESTINATION "${INCLUDE_INSTALL_DIR}/gin
+ 
+ add_custom_command(
+ 	OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/function.h
+-	COMMAND python ${CMAKE_CURRENT_SOURCE_DIR}/function.py -o ${CMAKE_CURRENT_BINARY_DIR}/function.h ${CMAKE_CURRENT_SOURCE_DIR}/function.hppy
++	COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/function.py -o ${CMAKE_CURRENT_BINARY_DIR}/function.h ${CMAKE_CURRENT_SOURCE_DIR}/function.hppy
+ 	DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/function.hppy ${CMAKE_CURRENT_SOURCE_DIR}/function.py)
+ 
+ add_custom_command(
+ 	OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/function.cpp
+-	COMMAND python ${CMAKE_CURRENT_SOURCE_DIR}/function.py -o ${CMAKE_CURRENT_BINARY_DIR}/function.cpp ${CMAKE_CURRENT_SOURCE_DIR}/function.cppy
++	COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/function.py -o ${CMAKE_CURRENT_BINARY_DIR}/function.cpp ${CMAKE_CURRENT_SOURCE_DIR}/function.cppy
+ 	DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/function.h ${CMAKE_CURRENT_SOURCE_DIR}/function.cppy ${CMAKE_CURRENT_SOURCE_DIR}/function.py)
+ 
+diff --git a/ginsh/CMakeLists.txt b/ginsh/CMakeLists.txt
+index c350a21a..5e408594 100644
+--- a/ginsh/CMakeLists.txt
++++ b/ginsh/CMakeLists.txt
+@@ -40,13 +40,13 @@ endif()
+ 
+ add_custom_command(
+ 	OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/ginsh_fcn_help.h
+-	COMMAND python ${CMAKE_CURRENT_SOURCE_DIR}/ginsh_fcn_help.py -o ginsh_fcn_help.h ${CMAKE_CURRENT_SOURCE_DIR}/ginsh.1.in
++	COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/ginsh_fcn_help.py -o ginsh_fcn_help.h ${CMAKE_CURRENT_SOURCE_DIR}/ginsh.1.in
+ 	DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/ginsh.1.in ${CMAKE_CURRENT_SOURCE_DIR}/ginsh_fcn_help.py
+ 	WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+ 
+ add_custom_command(
+ 	OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/ginsh_op_help.h
+-	COMMAND python ${CMAKE_CURRENT_SOURCE_DIR}/ginsh_op_help.py -o ginsh_op_help.h ${CMAKE_CURRENT_SOURCE_DIR}/ginsh.1.in
++	COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/ginsh_op_help.py -o ginsh_op_help.h ${CMAKE_CURRENT_SOURCE_DIR}/ginsh.1.in
+ 	DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/ginsh.1.in ${CMAKE_CURRENT_SOURCE_DIR}/ginsh_op_help.py
+ 	WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+ 
diff --git a/ginac.spec b/ginac.spec
index dfec29a..8ebb09a 100644
--- a/ginac.spec
+++ b/ginac.spec
@@ -2,11 +2,14 @@
 
 Name:             ginac
 Version:          1.7.4
-Release:          3%{?dist}
+Release:          4%{?dist}
 Summary:          C++ library for symbolic calculations
 License:          GPLv2+
 URL:              https://www.ginac.de/
 Source0:          https://www.ginac.de/%{name}-%{version}.tar.bz2
+# Submitted upstream: http://www.cebix.net/pipermail/ginac-list/2018-July/002214.html
+Patch0:           ginac.cmake-find-python.patch
+
 BuildRequires:    gcc-c++
 BuildRequires:    bison
 BuildRequires:    cln-devel
@@ -69,6 +72,12 @@ make -C doc/tutorial/ ginac_html
 rm -frv %{buildroot}%{_infodir}/dir
 find %{buildroot} -name '*.la' -delete -print
 
+for f in $(find %{buildroot} -name "*.py") ; do
+  sed -i.orig "s:^#\!/usr/bin/env\s\+python:#!%{__python2}:" $f
+  touch -r $f.orig $f
+  rm $f.orig
+done
+
 %check
 make check
 
@@ -100,6 +109,10 @@ fi
 %{_bindir}/*
 
 %changelog
+* Sat Jul 14 2018 Till Hofmann <thofmann@fedoraproject.org> - 1.7.4-4
+- Add patch to avoid using unversioned python in cmake
+- Replace unversioned python shebangs in all installed python files
+
 * Fri Jul 13 2018 Fedora Release Engineering <releng@fedoraproject.org> - 1.7.4-3
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_29_Mass_Rebuild