diff --git a/configure b/configure
index 5204869..7da2dac 100755
--- a/configure
+++ b/configure
@@ -7166,7 +7166,7 @@ else
         echo '%%'  > conftest.l
         if $pgac_candidate -t conftest.l 2>/dev/null | grep FLEX_SCANNER >/dev/null 2>&1; then
           pgac_flex_version=`$pgac_candidate --version 2>/dev/null`
-          if echo "$pgac_flex_version" | sed 's/[.a-z]/ /g' | $AWK '{ if ($1 = 2 && $2 = 5 && $3 >= 31) exit 0; else exit 1;}'
+          if echo "$pgac_flex_version" | sed 's/[.a-z]/ /g' | $AWK '{ if ($1 == 2 && ($2 > 5 || ($2 == 5 && $3 >= 31))) exit 0; else exit 1;}'
           then
             pgac_cv_path_flex=$pgac_candidate
             break 2