diff --git a/var/spack/repos/builtin/packages/ape/package.py b/var/spack/repos/builtin/packages/ape/package.py
index b1647798b52..48e436804f3 100644
--- a/var/spack/repos/builtin/packages/ape/package.py
+++ b/var/spack/repos/builtin/packages/ape/package.py
@@ -45,6 +45,13 @@ def install(self, spec, prefix):
             '--with-libxc-prefix=%s' % spec['libxc'].prefix
         ])
 
+        # When preprocessor expands macros (i.e. CFLAGS) defined as quoted
+        # strings the result may be > 132 chars and is terminated.
+        # This will look to a compiler as an Unterminated character constant
+        # and produce Line truncated errors. To vercome this, add flags to
+        # let compiler know that the entire line is meaningful.
+        # TODO: For the lack of better approach, assume that clang is mixed
+        # with GNU fortran.
         if spec.satisfies('%clang') or spec.satisfies('%gcc'):
             args.extend([
                 'FCFLAGS=-O2 -ffree-line-length-none'