diff --git a/interfaces-and-libraries.sh b/interfaces-and-libraries.sh
index 6ef70a156d..efe2a372a4 100755
--- a/interfaces-and-libraries.sh
+++ b/interfaces-and-libraries.sh
@@ -171,7 +171,7 @@ function setUpInterfacesAndLibraries()
 	if [ $BUILD_68K != false ]; then
 		echo "Converting 68K static libraries..."
 		for macobj in "${M68KLIBRARIES}/"*.o; do
-			if [ -r $macobj ]; then
+			if [ -r "$macobj" ]; then
 				libname=`basename "$macobj"`
 				libname=${libname%.o}
 				printf "    %30s => %-30s\n" ${libname}.o lib${libname}.a
@@ -203,17 +203,17 @@ function setUpInterfacesAndLibraries()
 				;;
 		esac
 
-		if [ -d ${PPCLIBRARIES} ]; then
+		if [ -d "${PPCLIBRARIES}" ]; then
 			echo "Copying static PPC libraries"
-			for obj in ${PPCLIBRARIES}/OpenT*.o ${PPCLIBRARIES}/CarbonAccessors.o ${PPCLIBRARIES}/CursorDevicesGlue.o; do
-				if [ -r $obj ]; then
+			for obj in "${PPCLIBRARIES}/OpenT*.o" "${PPCLIBRARIES}/CarbonAccessors.o" "${PPCLIBRARIES}/CursorDevicesGlue.o"; do
+				if [ -r "$obj" ]; then
 					# copy the library:
-					cp $obj $PREFIX/powerpc-apple-macos/lib/
+					cp "$obj" "$PREFIX/powerpc-apple-macos/lib/"
 
 					# and wrap it in a .a archive for convenience
-					lib=$PREFIX/powerpc-apple-macos/lib/lib`basename "${obj%.o}"`.a
-					rm -f $lib
-					$PREFIX/bin/powerpc-apple-macos-ar cqs $lib $obj
+					lib="$PREFIX"/powerpc-apple-macos/lib/lib`basename "${obj%.o}"`.a
+					rm -f "$lib"
+					powerpc-apple-macos-ar cqs "$lib" "$obj"
 				fi
 			done
 		fi
@@ -228,12 +228,13 @@ if [ "$0" = "$BASH_SOURCE" ]; then
 		exit 1
 	fi
 
-	PREFIX=$1
-	INTERFACES_DIR=$2
+	PREFIX="$1"
+	INTERFACES_DIR="$2"
 	BUILD_68K=${3:-true}
 	BUILD_PPC=${4:-true}
 	BUILD_CARBON=${5:-true}
 	SRC=$(cd `dirname $0` && pwd -P)
+    export PATH="$PREFIX/bin:$PATH"
 
 	locateAndCheckInterfacesAndLibraries
 	setUpInterfacesAndLibraries
diff --git a/prepare-headers.sh b/prepare-headers.sh
index b920b7673b..a39c9143b9 100644
--- a/prepare-headers.sh
+++ b/prepare-headers.sh
@@ -1,10 +1,10 @@
-IN=$1
-OUT=$2
+IN="$1"
+OUT="$2"
 
 # Make Mac OS X's tr and sed not complain that the files are not UTF-8
 export LC_ALL=C
 
-for file in $(cd $IN; ls *.h); do
+for file in $(cd "$IN"; ls *.h); do
 	# Filter by file names.
 	# Some CIncludes packages include the MPW standard library.
 	# Header files from that standard library would overwrite
@@ -52,12 +52,12 @@ for file in $(cd $IN; ls *.h); do
 	esac
 
 	if [ $USE = true ]; then
-		sed 's/\r$//' < $IN/$file | tr '\r' '\n' > $OUT/$file
+		sed 's/\r$//' < "$IN/$file" | tr '\r' '\n' > "$OUT/$file"
 	fi
 done
 
 ############################# ConditionalMacros.h #############################
-cat > $OUT/ConditionalMacros.h <<END_MARKER
+cat > "$OUT/ConditionalMacros.h" <<END_MARKER
 
 #ifndef __CONDITIONALMACROS__WRAP__
 #define __CONDITIONALMACROS__WRAP__
@@ -84,18 +84,18 @@ cat > $OUT/ConditionalMacros.h <<END_MARKER
 #define __DEBUGGING__  /* HACK: Disable Debugging.h because its vdprintf conflicts with stdio.h */
 END_MARKER
 
-sed 's/\r$//' < $IN/ConditionalMacros.h | tr '\r' '\n' | sed 's/__GNUC__/__GNUC_DISABLED__/g' >> $OUT/ConditionalMacros.h
+sed 's/\r$//' < "$IN/ConditionalMacros.h" | tr '\r' '\n' | sed 's/__GNUC__/__GNUC_DISABLED__/g' >> "$OUT/ConditionalMacros.h"
 
-cat >> $OUT/ConditionalMacros.h <<END_MARKER
+cat >> "$OUT/ConditionalMacros.h" <<END_MARKER
 
 
 #endif /* __CONDITIONALMACROS__WRAP__ */
 END_MARKER
 
 ############################# fp.h #############################
-if [ -r $IN/fp.h ]; then
+if [ -r "$IN/fp.h" ]; then
 
-cat > $OUT/fp.h <<END_MARKER
+cat > "$OUT/fp.h" <<END_MARKER
 
 #ifndef __FP__WRAP__
 #define __FP__WRAP__
@@ -123,11 +123,11 @@ END_MARKER
 fi
 
 ############################# MixedMode.h #############################
-sed 's/\r$//' < $IN/MixedMode.h | tr '\r' '\n' | sed 's/Opaque\#\#name\#\#\*/Opaque\#\#name \*/g' > $OUT/MixedMode.h
+sed 's/\r$//' < "$IN/MixedMode.h" | tr '\r' '\n' | sed 's/Opaque\#\#name\#\#\*/Opaque\#\#name \*/g' > "$OUT/MixedMode.h"
 
 ############################# CGBase.h #############################
-if [ -r $IN/CGBase.h ]; then
-cat > $OUT/CGBase.h <<END_MARKER
+if [ -r "$IN/CGBase.h" ]; then
+cat > "$OUT/CGBase.h" <<END_MARKER
 
 #ifndef __CGBASE__WRAP__
 #define __CGBASE__WRAP__
@@ -144,9 +144,9 @@ cat > $OUT/CGBase.h <<END_MARKER
 
 END_MARKER
 
-sed 's/\r$//' < $IN/CGBase.h | tr '\r' '\n' >> $OUT/CGBase.h
+sed 's/\r$//' < "$IN/CGBase.h" | tr '\r' '\n' >> "$OUT/CGBase.h"
 
-cat >> $OUT/CGBase.h <<END_MARKER
+cat >> "$OUT/CGBase.h" <<END_MARKER
 
 #undef u_int32_t __cgbase_incompatible_u_int32_t
 
@@ -158,16 +158,16 @@ END_MARKER
 fi
 
 for f in Types.h Memory.h Windows.h Errors.h; do
-	if [ ! -r $IN/$f ]; then
-		echo "#include \"Mac$f\"" > $OUT/$f
-	elif [ ! -r $IN/Mac$f ]; then
-		echo "#include \"$f\"" > $OUT/Mac$f
+	if [ ! -r "$IN/$f" ]; then
+		echo "#include \"Mac$f\"" > "$OUT/$f"
+	elif [ ! -r "$IN/Mac$f" ]; then
+		echo "#include \"$f\"" > "$OUT/Mac$f"
 	fi
 done
 
-if [ -d $IN/CoreFoundation ]; then
-	mkdir -p $OUT/CoreFoundation
-	for file in $(cd $IN; ls CoreFoundation/*.h); do
-		sed 's/\r$//' < $IN/$file | tr '\r' '\n' > $OUT/$file
+if [ -d "$IN/CoreFoundation" ]; then
+	mkdir -p "$OUT/CoreFoundation"
+	for file in $(cd "$IN"; ls CoreFoundation/*.h); do
+		sed 's/\r$//' < "$IN/$file" | tr '\r' '\n' > "$OUT/$file"
 	done
 fi
diff --git a/prepare-rincludes.sh b/prepare-rincludes.sh
index 0143861831..30ccb30bc4 100644
--- a/prepare-rincludes.sh
+++ b/prepare-rincludes.sh
@@ -1,11 +1,11 @@
-IN=$1
-OUT=$2
+IN="$1"
+OUT="$2"
 
 # Make Mac OS X's tr and sed not complain that the files are not UTF-8
 export LC_ALL=C
 
 # cp $IN/[A-Z]*.r $OUT/
-for file in $(cd $IN; ls [A-Z]*.r); do
+for file in $(cd "$IN"; ls [A-Z]*.r); do
 	tr '\r' '\n' < $IN/$file > $OUT/$file
 done