diff --git a/contrib/build-osx/make_osx b/contrib/build-osx/make_osx
index 70793499d..a2f7b50f8 100755
--- a/contrib/build-osx/make_osx
+++ b/contrib/build-osx/make_osx
@@ -37,7 +37,7 @@ fail "Unable to use Python $PYTHON_VERSION"
 
 
 info "Installing pyinstaller"
-python3 -m pip install pyinstaller -I --user || fail "Could not install pyinstaller"
+python3 -m pip install git+https://github.com/ecdsa/pyinstaller@fix_2952 -I --user || fail "Could not install pyinstaller"
 
 info "Using these versions for building $PACKAGE:"
 sw_vers
diff --git a/contrib/build-wine/build.sh b/contrib/build-wine/build.sh
index a4e39adf1..8bf650626 100755
--- a/contrib/build-wine/build.sh
+++ b/contrib/build-wine/build.sh
@@ -13,8 +13,7 @@ echo "Clearing $here/build and $here/dist..."
 rm "$here"/build/* -rf
 rm "$here"/dist/* -rf
 
-$here/prepare-wine.sh && \
-$here/prepare-pyinstaller.sh || exit 1
+$here/prepare-wine.sh || exit 1
 
 echo "Resetting modification time in C:\Python..."
 # (Because of some bugs in pyinstaller)
diff --git a/contrib/build-wine/prepare-pyinstaller.sh b/contrib/build-wine/prepare-pyinstaller.sh
deleted file mode 100755
index cf8a326cd..000000000
--- a/contrib/build-wine/prepare-pyinstaller.sh
+++ /dev/null
@@ -1,24 +0,0 @@
-#!/bin/bash
-PYTHON_VERSION=3.5.4
-
-PYINSTALLER_GIT_URL=https://github.com/ecdsa/pyinstaller.git
-BRANCH=fix_2952
-
-export WINEPREFIX=/opt/wine64
-PYHOME=c:/python$PYTHON_VERSION
-PYTHON="wine $PYHOME/python.exe -OO -B"
-
-cd `dirname $0`
-set -e
-cd tmp
-if [ ! -d "pyinstaller" ]; then
-    git clone -b $BRANCH $PYINSTALLER_GIT_URL pyinstaller
-fi
-
-cd pyinstaller
-git pull
-git checkout $BRANCH
-$PYTHON setup.py install
-cd ..
-
-wine "C:/python$PYTHON_VERSION/scripts/pyinstaller.exe" -v
diff --git a/contrib/build-wine/prepare-wine.sh b/contrib/build-wine/prepare-wine.sh
index 42828be77..d62b4c63d 100755
--- a/contrib/build-wine/prepare-wine.sh
+++ b/contrib/build-wine/prepare-wine.sh
@@ -80,6 +80,10 @@ $PYTHON -m pip install win_inet_pton==1.0.1
 
 $PYTHON -m pip install -r ../../deterministic-build/requirements-binaries.txt
 
+# Install PyInstaller
+
+$PYTHON -m pip install git+https://github.com/ecdsa/pyinstaller@fix_2952
+
 # Install ZBar
 #wget -q -O zbar.exe "https://sourceforge.net/projects/zbar/files/zbar/0.10/zbar-0.10-setup.exe/download"
 #wine zbar.exe