diff --git a/applications/utilities/mesh/conversion/ansysToFoam/Make/options b/applications/utilities/mesh/conversion/ansysToFoam/Make/options
index 2a474c782..19d7931b0 100644
--- a/applications/utilities/mesh/conversion/ansysToFoam/Make/options
+++ b/applications/utilities/mesh/conversion/ansysToFoam/Make/options
@@ -1,4 +1,4 @@
-ifneq ($(FLEX_DIR), "")
+ifneq ($(FLEX_DIR),)
 EXE_INC = \
     -I$(FLEX_DIR)/include
 endif
diff --git a/applications/utilities/mesh/conversion/fluent3DMeshToElmer/Make/options b/applications/utilities/mesh/conversion/fluent3DMeshToElmer/Make/options
index a1aeaa40f..65092cedc 100644
--- a/applications/utilities/mesh/conversion/fluent3DMeshToElmer/Make/options
+++ b/applications/utilities/mesh/conversion/fluent3DMeshToElmer/Make/options
@@ -1,4 +1,4 @@
-ifneq ($(FLEX_DIR), "")
+ifneq ($(FLEX_DIR),)
 EXE_INC = \
     -I$(FLEX_DIR)/include \
     -I$(LIB_SRC)/meshTools/lnInclude \
diff --git a/applications/utilities/mesh/conversion/fluent3DMeshToFoam/Make/options b/applications/utilities/mesh/conversion/fluent3DMeshToFoam/Make/options
index 6a9d33e58..1f884ec58 100644
--- a/applications/utilities/mesh/conversion/fluent3DMeshToFoam/Make/options
+++ b/applications/utilities/mesh/conversion/fluent3DMeshToFoam/Make/options
@@ -1,4 +1,4 @@
-ifneq ($(FLEX_DIR), "")
+ifneq ($(FLEX_DIR),)
 EXE_INC = \
     -I$(FLEX_DIR)/include \
     -I$(LIB_SRC)/meshTools/lnInclude \
diff --git a/applications/utilities/mesh/conversion/fluentMeshToFoam/Make/options b/applications/utilities/mesh/conversion/fluentMeshToFoam/Make/options
index 6a9d33e58..1f884ec58 100644
--- a/applications/utilities/mesh/conversion/fluentMeshToFoam/Make/options
+++ b/applications/utilities/mesh/conversion/fluentMeshToFoam/Make/options
@@ -1,4 +1,4 @@
-ifneq ($(FLEX_DIR), "")
+ifneq ($(FLEX_DIR),)
 EXE_INC = \
     -I$(FLEX_DIR)/include \
     -I$(LIB_SRC)/meshTools/lnInclude \
diff --git a/applications/utilities/mesh/conversion/gambitToFoam/Make/options b/applications/utilities/mesh/conversion/gambitToFoam/Make/options
index 2a474c782..19d7931b0 100644
--- a/applications/utilities/mesh/conversion/gambitToFoam/Make/options
+++ b/applications/utilities/mesh/conversion/gambitToFoam/Make/options
@@ -1,4 +1,4 @@
-ifneq ($(FLEX_DIR), "")
+ifneq ($(FLEX_DIR),)
 EXE_INC = \
     -I$(FLEX_DIR)/include
 endif
diff --git a/applications/utilities/preProcessing/fluentDataToFoam/Make/options b/applications/utilities/preProcessing/fluentDataToFoam/Make/options
index 62398dc0d..8345bb6f1 100644
--- a/applications/utilities/preProcessing/fluentDataToFoam/Make/options
+++ b/applications/utilities/preProcessing/fluentDataToFoam/Make/options
@@ -1,4 +1,4 @@
-ifneq ($(FLEX_DIR), "")
+ifneq ($(FLEX_DIR),)
 EXE_INC = \
     -I$(FLEX_DIR)/include \
     -I$(LIB_SRC)/finiteVolume/lnInclude
diff --git a/applications/utilities/thermophysical/chemkinToFoam/Make/options b/applications/utilities/thermophysical/chemkinToFoam/Make/options
index 52a0cb8ee..491c0bd80 100644
--- a/applications/utilities/thermophysical/chemkinToFoam/Make/options
+++ b/applications/utilities/thermophysical/chemkinToFoam/Make/options
@@ -1,4 +1,4 @@
-ifneq ($(FLEX_DIR), "")
+ifneq ($(FLEX_DIR),)
 EXE_INC = \
     -I$(FLEX_DIR)/include \
     -I$(LIB_SRC)/thermophysicalModels/specie/lnInclude \
diff --git a/src/meshTools/Make/options b/src/meshTools/Make/options
index be1f5d5f9..b9b0d1e17 100644
--- a/src/meshTools/Make/options
+++ b/src/meshTools/Make/options
@@ -1,4 +1,4 @@
-ifneq ($(FLEX_DIR), "")
+ifneq ($(FLEX_DIR),)
 EXE_INC = \
     -I$(FLEX_DIR)/include \
     -I$(LIB_SRC)/meshTools/lnInclude \
diff --git a/src/surfMesh/Make/options b/src/surfMesh/Make/options
index 317a32f40..19d7931b0 100644
--- a/src/surfMesh/Make/options
+++ b/src/surfMesh/Make/options
@@ -1,4 +1,4 @@
-ifneq ($(FLEX_DIR), "")
+ifneq ($(FLEX_DIR),)
 EXE_INC = \
     -I$(FLEX_DIR)/include
-endif
\ No newline at end of file
+endif
diff --git a/src/thermophysicalModels/reactionThermo/Make/options b/src/thermophysicalModels/reactionThermo/Make/options
index 8398adf7b..39aecf5c4 100644
--- a/src/thermophysicalModels/reactionThermo/Make/options
+++ b/src/thermophysicalModels/reactionThermo/Make/options
@@ -1,4 +1,4 @@
-ifneq ($(FLEX_DIR), "")
+ifneq ($(FLEX_DIR),)
 EXE_INC = \
     -I$(FLEX_DIR)/include \
     -I$(LIB_SRC)/finiteVolume/lnInclude \