diff --git a/pkgs/applications/science/astronomy/gildas/default.nix b/pkgs/applications/science/astronomy/gildas/default.nix
index da575b5cdd4..bd4587bf227 100644
--- a/pkgs/applications/science/astronomy/gildas/default.nix
+++ b/pkgs/applications/science/astronomy/gildas/default.nix
@@ -1,5 +1,5 @@
 { stdenv, fetchurl, gtk2-x11 , pkgconfig , python27 , gfortran , lesstif
-, cfitsio , getopt , perl , groff , which , openblas
+, cfitsio , getopt , perl , groff , which
 }:
 
 let
@@ -20,14 +20,14 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ pkgconfig groff perl getopt gfortran which ];
 
-  buildInputs = [ gtk2-x11 lesstif cfitsio python27Env openblas ];
+  buildInputs = [ gtk2-x11 lesstif cfitsio python27Env ];
 
-  patches = [ ./wrapper.patch ./return-error-code.patch ./openblas.patch ./clang.patch ];
+  patches = [ ./wrapper.patch ./return-error-code.patch ./clang.patch ];
 
   configurePhase=''
     substituteInPlace admin/wrapper.sh --replace '%%OUT%%' $out
     substituteInPlace admin/wrapper.sh --replace '%%PYTHONHOME%%' ${python27Env}
-    source admin/gildas-env.sh -c gfortran -o openmp -s ${openblas}/lib
+    source admin/gildas-env.sh -c gfortran -o openmp
     echo "gag_doc:        $out/share/doc/" >> kernel/etc/gag.dico.lcl
   '';
 
diff --git a/pkgs/applications/science/astronomy/gildas/openblas.patch b/pkgs/applications/science/astronomy/gildas/openblas.patch
deleted file mode 100644
index 4236b50796c..00000000000
--- a/pkgs/applications/science/astronomy/gildas/openblas.patch
+++ /dev/null
@@ -1,96 +0,0 @@
-diff -ruN gildas-src-may18a.orig/admin/gildas-env.sh gildas-src-may18a/admin/gildas-env.sh
---- gildas-src-may18a.orig/admin/gildas-env.sh	2018-04-24 18:20:08.000000000 +0200
-+++ gildas-src-may18a/admin/gildas-env.sh	2018-05-04 16:39:18.982253471 +0200
-@@ -430,7 +430,7 @@
-         # dot (e.g. so.3 is not counted), because e.g. /usr/lib64/liblapack.so.3
-         # is useless and can not be found by the linker on command lines like
-         # "-L/usr/lib -llapack"
--        occurences=`\ls ${2}/${1}* 2> /dev/null | \grep -v "${2}/${1}.*\." | \wc -l`
-+        occurences=`\ls -l ${2}/${1}{so,a,h} 2> /dev/null | \wc -l`
-         if [ ${occurences} -ge 1 ]; then
-             \return 0
-         else
-@@ -458,11 +458,9 @@
-     SDM_MISSING=
-     #
-     for DIR in $GAGENV_SEARCH_PATH; do
--        if file_present "liblapack." "${DIR}"; then
-+        if file_present "libopenblas." "${DIR}"; then
-             LAPACK_PRESENT=yes
-             LAPACK_LIB_DIR=$DIR
--        fi
--        if file_present "libblas." "${DIR}"; then
-             BLAS_PRESENT=yes
-             BLAS_LIB_DIR=$DIR
-         fi
-@@ -493,7 +491,7 @@
-     X11_LIB=no
-     #
-     for DIR in $INC_PATH; do
--        if file_present "X.h" "${DIR}/X11"; then
-+        if file_present "X." "${DIR}/X11"; then
-             X11_INC=yes
-             X11_INC_DIR=$DIR
-         fi
-diff -ruN gildas-src-may18a.orig/admin/Makefile.build gildas-src-may18a/admin/Makefile.build
---- gildas-src-may18a.orig/admin/Makefile.build	2018-03-19 17:48:07.000000000 +0100
-+++ gildas-src-may18a/admin/Makefile.build	2018-05-04 16:39:18.982253471 +0200
-@@ -398,9 +398,7 @@
- # only the shared libraries are installed (i.e. the corresponding archive
- # libraries are missing).
- 
---lblas:
--
---llapack:
-+-lopenblas:
- 
- -lslatec:
- 
-diff -ruN gildas-src-may18a.orig/admin/Makefile.def gildas-src-may18a/admin/Makefile.def
---- gildas-src-may18a.orig/admin/Makefile.def	2018-03-21 17:53:34.000000000 +0100
-+++ gildas-src-may18a/admin/Makefile.def	2018-05-04 16:41:59.233518207 +0200
-@@ -206,7 +206,7 @@
- ###########################################################################
- # Other defaults
- 
--LINEAR = lapack
-+LINEAR = openblas
- GLOBAL_DIRTY = $(builddir) *~ TAGS ChangeLog* Makefile.bak
- 
- ###########################################################################
-@@ -515,7 +515,7 @@
- ###########################################################################
- # Kernel libraries
- 
--LEGACY_LIBS = -lslatec -llapack -lblas
-+LEGACY_LIBS = -lslatec -lopenblas
- _GAG_LIBS = -lggui -lgcore -lgio -lgfits -lgwcs -lgmath -lgsys -lginc
- ifndef GAG_WIN32
-   GAG_LIBS = $(_GAG_LIBS)
-diff -ruN gildas-src-may18a.orig/legacy/slatec/Makefile gildas-src-may18a/legacy/slatec/Makefile
---- gildas-src-may18a.orig/legacy/slatec/Makefile	2014-12-09 11:31:56.000000000 +0100
-+++ gildas-src-may18a/legacy/slatec/Makefile	2018-05-04 16:39:18.982253471 +0200
-@@ -24,7 +24,7 @@
- U-all.o V-all.o W-all.o X-all.o Y-all.o Z-all.o d1mach.o i1mach.o pimach.o  \
- r1mach.o dummy.o P-all.o P-value.o Dp-1vlu.o 
- 
--LIB_DEPENDS = -llapack -lblas
-+LIB_DEPENDS = -lopenblas
- 
- ifeq ($(GAG_COMPILER_FKIND),ifc)
-   OPTION_FFLAGS = 
-diff -ruN gildas-src-may18a.orig/packages/clic/lib/Makefile gildas-src-may18a/packages/clic/lib/Makefile
---- gildas-src-may18a.orig/packages/clic/lib/Makefile	2018-01-16 11:53:15.000000000 +0100
-+++ gildas-src-may18a/packages/clic/lib/Makefile	2018-05-04 16:39:18.982253471 +0200
-@@ -56,9 +56,9 @@
- sg_line_table.o table_passband.o clic_index.o clic_blank.o
- 
- # Mathematical library dependency
--ifeq ($(LINEAR),lapack)
-+ifeq ($(LINEAR),openblas)
-   LINEAR_LIB_OBJECTS = singular.o mth_lapack.o
--  LINEAR_LIB_DEPENDS = -llapack -lblas
-+  LINEAR_LIB_DEPENDS = -lopenblas
- else 
-   ifeq ($(LINEAR),nag)
-     LINEAR_LIB_OBJECTS = mth_nag.o