diff --git a/build.sh b/build.sh
index 43bd1d13a..d9bc39f9d 100755
--- a/build.sh
+++ b/build.sh
@@ -32,17 +32,27 @@ popd
 bash "$ROOT_DIR/src/thirdparty/download_thirdparty.sh"
 bash "$ROOT_DIR/src/thirdparty/build_thirdparty.sh" $PYTHON_EXECUTABLE
 
+# Get the directory of the Python executable.
+PYTHON_EXECUTABLE_DIR=$(dirname $PYTHON_EXECUTABLE)
+
 # Now build everything.
 pushd "$ROOT_DIR/python/ray/core"
   # We use these variables to set PKG_CONFIG_PATH, which is important so that
   # in cmake, pkg-config can find plasma.
   TP_DIR=$ROOT_DIR/src/thirdparty
   ARROW_HOME=$TP_DIR/arrow/cpp/build/cpp-install
-  if [ "$VALGRIND" = "1" ]
-  then
-    PKG_CONFIG_PATH=$ARROW_HOME/lib/pkgconfig cmake -DCMAKE_BUILD_TYPE=Debug ../../..
+  if [[ "$VALGRIND" = "1" ]]; then
+    # Pass a slightly different path into this command so that cmake finds the
+    # right Python interpreter and libraries.
+    PATH=$PYTHON_EXECUTABLE_DIR:$PATH \
+    PKG_CONFIG_PATH=$ARROW_HOME/lib/pkgconfig \
+    cmake -DCMAKE_BUILD_TYPE=Debug ../../..
   else
-    PKG_CONFIG_PATH=$ARROW_HOME/lib/pkgconfig cmake -DCMAKE_BUILD_TYPE=Release ../../..
+    # Pass a slightly different path into this command so that cmake finds the
+    # right Python interpreter and libraries.
+    PATH=$PYTHON_EXECUTABLE_DIR:$PATH \
+    PKG_CONFIG_PATH=$ARROW_HOME/lib/pkgconfig \
+    cmake -DCMAKE_BUILD_TYPE=Release ../../..
   fi
   make clean
   make -j${PARALLEL}
diff --git a/src/thirdparty/build_thirdparty.sh b/src/thirdparty/build_thirdparty.sh
index be7095e5b..c4f75e1c4 100755
--- a/src/thirdparty/build_thirdparty.sh
+++ b/src/thirdparty/build_thirdparty.sh
@@ -31,6 +31,13 @@ cd $TP_DIR/arrow/cpp
 mkdir -p $TP_DIR/arrow/cpp/build
 cd $TP_DIR/arrow/cpp/build
 export ARROW_HOME=$TP_DIR/arrow/cpp/build/cpp-install
+
+# Get the directory of the Python executable.
+PYTHON_EXECUTABLE_DIR=$(dirname $PYTHON_EXECUTABLE)
+
+# Pass a slightly different path into this command so that cmake finds the right
+# Python interpreter and libraries.
+PATH=$PYTHON_EXECUTABLE_DIR:$PATH \
 cmake -DCMAKE_BUILD_TYPE=Release \
       -DCMAKE_C_FLAGS="-g -O3" \
       -DCMAKE_CXX_FLAGS="-g -O3" \