diff --git a/doxygen.spec b/doxygen.spec
index 9628f5c..a8cb7f6 100644
--- a/doxygen.spec
+++ b/doxygen.spec
@@ -50,7 +50,7 @@ BuildRequires: flex
 BuildRequires: bison
 BuildRequires: cmake
 BuildRequires: git
-%if %{xapian_core_support} == "ON"
+%if "x%{?xapian_core_support}" == "xON"
 BuildRequires: xapian-core-devel
 BuildRequires: zlib-devel
 %endif
@@ -155,7 +155,7 @@ cp doc/*.1 %{buildroot}/%{_mandir}/man1/
 rm -f %{buildroot}/%{_mandir}/man1/doxywizard.1*
 %endif
 
-%if %{xapian_core_support} == "OFF"
+%if "x%{?xapian_core_support}" == "xOFF"
 rm -f %{buildroot}/%{_mandir}/man1/doxyindexer.1* %{buildroot}/%{_mandir}/man1/doxysearch.1*
 %endif
 
@@ -180,7 +180,7 @@ make tests -C %{BuildDir}
 %endif
 %{_bindir}/doxygen
 %{_mandir}/man1/doxygen.1*
-%if %{xapian_core_support} == "ON"
+%if "x%{?xapian_core_support}" == "xON"
 %{_mandir}/man1/doxyindexer.1*
 %{_mandir}/man1/doxysearch.1*
 %endif