diff --git a/cmake/modules/FindYACC.cmake b/cmake/modules/FindYACC.cmake
index c96f87b389..c4e889f4ac 100644
--- a/cmake/modules/FindYACC.cmake
+++ b/cmake/modules/FindYACC.cmake
@@ -22,9 +22,24 @@ FIND_PACKAGE_HANDLE_STANDARD_ARGS(YACC DEFAULT_MSG YACC_EXECUTABLE)
 
 MARK_AS_ADVANCED(YACC_EXECUTABLE)
 
+# Specifying "%pure-parser" will fail with a deprecation warning in
+# Bison 3.4 and later. Specifying "%define api.pure" doesn't work with
+# Berkeley YACC and older versions of Bison (such as 2.3, which ships
+# with macOS). If we're using Bison and it's new, configure our .y.in
+# files with "%define api.pure", otherwise use "%pure-parser".
+set(YACC_PURE_PARSER_DIRECTIVE "%pure-parser")
+if(YACC_EXECUTABLE)
+    execute_process(COMMAND ${YACC_EXECUTABLE} -V OUTPUT_VARIABLE _yacc_full_version)
+    string(REGEX MATCH "[1-9]+\.[0-9]+" _yacc_major_minor ${_yacc_full_version})
+    if (_yacc_full_version MATCHES "GNU Bison" AND _yacc_major_minor VERSION_GREATER "2.6")
+        set(YACC_PURE_PARSER_DIRECTIVE "%define api.pure")
+    endif()
+endif()
+
 MACRO(ADD_YACC_FILES _source _generated)
     FOREACH (_current_FILE ${ARGN})
-      GET_FILENAME_COMPONENT(_in ${_current_FILE} ABSOLUTE)
+      configure_file(${_current_FILE}.in ${_current_FILE})
+      GET_FILENAME_COMPONENT(_in ${CMAKE_CURRENT_BINARY_DIR}/${_current_FILE} ABSOLUTE)
       GET_FILENAME_COMPONENT(_basename ${_current_FILE} NAME_WE)
 
       SET(_out ${CMAKE_CURRENT_BINARY_DIR}/${_basename}.c)
diff --git a/epan/protobuf_lang.y b/epan/protobuf_lang.y.in
similarity index 98%
rename from epan/protobuf_lang.y
rename to epan/protobuf_lang.y.in
index 1e3fab939a..b031bfb6c5 100644
--- a/epan/protobuf_lang.y
+++ b/epan/protobuf_lang.y.in
@@ -1,11 +1,11 @@
 /*
  * We want a reentrant parser.
- * For now ignore the wdeprecated warning recommending
- * %define api.pure
- * https://code.wireshark.org/review/#/c/33771/
- * "This doesn't work with Berkeley YACC, and I'd *really* prefer not to require Bison."
+ * Berkeley YACC and older versions of Bison use "%pure-parser" and newer
+ * versions of Bison use "%define api.pure".
+ * As https://code.wireshark.org/review/#/c/33771/
+ * says, "This doesn't work with Berkeley YACC, and I'd *really* prefer not to require Bison."
  */
-%pure-parser
+${YACC_PURE_PARSER_DIRECTIVE}
 
 /*
  * We also want a reentrant scanner, so we have to pass the
diff --git a/wiretap/ascend.y b/wiretap/ascend.y.in
similarity index 98%
rename from wiretap/ascend.y
rename to wiretap/ascend.y.in
index b19a0464b0..cbc9f91a7b 100644
--- a/wiretap/ascend.y
+++ b/wiretap/ascend.y.in
@@ -1,11 +1,11 @@
 /*
  * We want a reentrant parser.
-  * For now ignore the wdeprecated warning recommending
- * %define api.pure
- * https://code.wireshark.org/review/#/c/33771/
- * "This doesn't work with Berkeley YACC, and I'd *really* prefer not to require Bison."
+ * Berkeley YACC and older versions of Bison use "%pure-parser" and newer
+ * versions of Bison use "%define api.pure".
+ * As https://code.wireshark.org/review/#/c/33771/
+ * says, "This doesn't work with Berkeley YACC, and I'd *really* prefer not to require Bison."
  */
-%pure-parser
+${YACC_PURE_PARSER_DIRECTIVE}
 
 /*
  * We also want a reentrant scanner, so we have to pass the