--- a/configure.ac
+++ b/configure.ac
@@ -571,7 +571,7 @@ if test "x${use_modules}" != "xno"; then
   LDFLAGS=$saved_ldflags
   LIBS=$saved_libs
 
-  if test "x$have_ltdl" == "xno"; then
+  if test "x$have_ltdl" = "xno"; then
     AC_MSG_ERROR([libltdl is required to build modules.  Please either specify the location of the libltdl library using --with-ltdl=PREFIX or else disable the building of modules by using --disable-modules])
   fi
 
@@ -601,18 +601,18 @@ AC_SUBST([LIBLTDL])
 AC_SUBST([LTDLINCL])
 
 dnl check if we found a C++ compiler
-if test "x$CXX" == "x"; then
+if test "x$CXX" = "x"; then
   make_cxxbindings=no
 fi
 
 dnl check if we found a Fortran 77 compiler
-if test "x$F77" == "x"; then
+if test "x$F77" = "x"; then
   make_f77bindings=no
   make_f95bindings=no
 fi
 
 dnl check if we found a free-form Fortran compiler
-if test "x$FC" == "x"; then
+if test "x$FC" = "x"; then
   make_f95bindings=no
 fi
 
@@ -641,7 +641,7 @@ fi
 dnl F77 stuff
 if test "x$make_f77bindings" != "xno"; then
   AC_F77_WRAPPERS
-  if test "x$ac_cv_f77_mangling" == "xunknown"; then
+  if test "x$ac_cv_f77_mangling" = "xunknown"; then
     make_f77bindings=no
     make_f95bindings=no
   fi
@@ -1065,7 +1065,7 @@ else
   AC_MSG_RESULT([$use_slim])
   AC_MSG_CHECKING([for zzip support])
   AC_MSG_RESULT([$use_zzip])
-  if test "$use_slim$use_zzip" == "yesyes"; then
+  if test "$use_slim$use_zzip" = "yesyes"; then
     if test $zzslim_override = "yes"; then
       AC_MSG_CHECKING([for zzslim support])
       AC_MSG_RESULT([yes (forced)])
@@ -1200,11 +1200,11 @@ AC_CONFIG_FILES([test/Makefile])
 AC_CONFIG_FILES([util/Makefile])
 
 dnl Automake conditionals
-AM_CONDITIONAL(GETDATA_DEBUG, [test "x$enable_debug" == "xyes"])
+AM_CONDITIONAL(GETDATA_DEBUG, [test "x$enable_debug" = "xyes"])
 AM_CONDITIONAL(HAVE_SED, [ test "x${SED}" != 'x' ])
 AM_CONDITIONAL(INTEL_F77_COMPILER,
-               [test "x$gd_cv_f77_compiler_intel" == "xyes"])
-AM_CONDITIONAL(INTEL_FC_COMPILER, [test "x$gd_cv_fc_compiler_intel" == "xyes"])
+               [test "x$gd_cv_f77_compiler_intel" = "xyes"])
+AM_CONDITIONAL(INTEL_FC_COMPILER, [test "x$gd_cv_fc_compiler_intel" = "xyes"])
 AM_CONDITIONAL(INCLUDE_LEGACY_API, [test "x$include_legacy_api" != "xno"])
 AM_CONDITIONAL(MAKE_CXXBINDINGS, [test "x$make_cxxbindings" = "xyes"])
 AM_CONDITIONAL(MAKE_F77BINDINGS, [test "x$make_f77bindings" != "xno"])