diff --git a/qtinterface/tqt-replace b/qtinterface/tqt-replace
index da752d2..45e1cff 100755
--- a/qtinterface/tqt-replace
+++ b/qtinterface/tqt-replace
@@ -1,7 +1,7 @@
 #!/bin/bash
 QT_VER=X
 
-if [[ $1 == "" ]]; then
+if [[ "$1" == "" ]]; then
 	echo "Usage: tqt-replace <input_file>"
 else
 	sed -i 's/^TQ\([^T_]\)/Q\1/g' "$1"
diff --git a/qtinterface/tqt-replace-stream b/qtinterface/tqt-replace-stream
index ff0d08d..ccf1ab0 100755
--- a/qtinterface/tqt-replace-stream
+++ b/qtinterface/tqt-replace-stream
@@ -1,10 +1,10 @@
 #!/bin/bash
 QT_VER=X
 
-if [[ $1 == "" ]]; then
+if [[ "$1" == "" ]]; then
 	echo "Usage: tqt-replace-stream <filename>"
 else
-	cat $1 | \
+	cat "$1" | \
 	sed 's/^TQ\([^T_]\)/Q\1/g' | \
 	sed 's/\([^_]\)TQ\([^T_]\)/\1Q\2/g' | \
 	sed 's/TQT\([^_]\)/QT\1/g' | \
diff --git a/qtinterface/tqt-replace-stream-tqt3.cmake b/qtinterface/tqt-replace-stream-tqt3.cmake
index c30e562..14f7308 100755
--- a/qtinterface/tqt-replace-stream-tqt3.cmake
+++ b/qtinterface/tqt-replace-stream-tqt3.cmake
@@ -1,8 +1,8 @@
 #!/bin/bash
 QT_VERSION=@QT_VERSION@
 
-if [[ $1 == "" ]]; then
+if [[ "$1" == "" ]]; then
 	echo "Usage: tqt-replace-stream <filename>"
 else
-	cat $1 | sed 's/^Q_OBJECT/TQ_OBJECT/g' | sed 's/\([^T]\)Q_OBJECT/\1TQ_OBJECT/g'
+	cat "$1" | sed 's/^Q_OBJECT/TQ_OBJECT/g' | sed 's/\([^T]\)Q_OBJECT/\1TQ_OBJECT/g'
 fi
diff --git a/qtinterface/tqt-replace-stream.cmake b/qtinterface/tqt-replace-stream.cmake
index 3f8daca..fcaeced 100755
--- a/qtinterface/tqt-replace-stream.cmake
+++ b/qtinterface/tqt-replace-stream.cmake
@@ -1,10 +1,10 @@
 #!/bin/bash
 QT_VERSION=@QT_VERSION@
 
-if [[ $1 == "" ]]; then
+if [[ "$1" == "" ]]; then
 	echo "Usage: tqt-replace-stream <filename>"
 else
-	cat $1 | \
+	cat "$1" | \
 	sed 's/^TQ\([^T_]\)/Q\1/g' | \
 	sed 's/\([^_]\)TQ\([^T_]\)/\1Q\2/g' | \
 	sed 's/TQT\([^_]\)/QT\1/g' | \
diff --git a/qtinterface/tqt-replace-tqt3.cmake b/qtinterface/tqt-replace-tqt3.cmake
index cb7de9c..413dee5 100755
--- a/qtinterface/tqt-replace-tqt3.cmake
+++ b/qtinterface/tqt-replace-tqt3.cmake
@@ -1,7 +1,7 @@
 #!/bin/bash
 QT_VERSION=@QT_VERSION@
 
-if [[ $1 == "" ]]; then
+if [[ "$1" == "" ]]; then
 	echo "Usage: tqt-replace <input_file>"
 else
 	sed -i 's/Q_SLOTS>/slots>/g' "$1"
diff --git a/qtinterface/tqt-replace.cmake b/qtinterface/tqt-replace.cmake
index 282b1e8..15b4b6f 100755
--- a/qtinterface/tqt-replace.cmake
+++ b/qtinterface/tqt-replace.cmake
@@ -1,7 +1,7 @@
 #!/bin/bash
 QT_VERSION=@QT_VERSION@
 
-if [[ $1 == "" ]]; then
+if [[ "$1" == "" ]]; then
 	echo "Usage: tqt-replace <input_file>"
 else
 	sed -i 's/^TQ\([^T_]\)/Q\1/g' "$1"