diff --git a/.gitattributes b/.gitattributes
index cb4033a47d63786ebe95ba10a95ddfc906dd7738..814b5192782889c63c4185edd2b033ca4b1e8c05 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -236,7 +236,7 @@ README* header_spec=.ignore
 # HEADER_SPEC: others #
 #######################
 
-/configure.in header_spec=CEA_INRIA_LGPL
+/configure.ac header_spec=CEA_INRIA_LGPL
 
 /doc/aorai/Makefile header_spec=AORAI_LGPL
 
diff --git a/Makefile b/Makefile
index b3735d0559e79e224576485d3d512e96448481ac..ac2e4c824b09c1e6f28f8ebf537ded20e7896b84 100644
--- a/Makefile
+++ b/Makefile
@@ -68,7 +68,7 @@ MINOR_VERSION=$(shell $(SED) -E 's/^[0-9]+\.([0-9]+).*/\1/' VERSION)
 VERSION_CODENAME=$(shell $(CAT) VERSION_CODENAME)
 
 # File used by dune to build src/kernel_internals/runtime/fc_config.ml
-config.sed: VERSION share/Makefile.config share/Makefile.common Makefile configure.in
+config.sed: VERSION share/Makefile.config share/Makefile.common Makefile configure.ac
 	@echo "# generated file" > $@
 	@echo "s|@VERSION@|$(VERSION)|" >> $@
 	@echo "s|@VERSION_CODENAME@|$(VERSION_CODENAME)|" >> $@
@@ -88,7 +88,7 @@ clean:: purge-tests # to be done before a "dune" command
 	rm -rf _build .merlin config.sed autom4te.cache
 
 ########################################################################
-# Makefile.config is rebuilt whenever configure.in is modified         #
+# Makefile.config is rebuilt whenever configure.ac is modified         #
 ########################################################################
 
 share/Makefile.config: share/Makefile.config.in config.status
@@ -105,7 +105,7 @@ config.status: configure
 	$(PRINT_MAKING) $@
 	./config.status --recheck
 
-configure: configure.in .force-reconfigure
+configure: configure.ac .force-reconfigure
 	$(PRINT_MAKING) $@
 	autoconf -f
 
diff --git a/configure.in b/configure.ac
similarity index 100%
rename from configure.in
rename to configure.ac