--- a/meson.build
+++ b/meson.build
@@ -27,7 +27,7 @@
     #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
     __attribute__((deprecated)) void test(void) {}
 ''')
-  conf_data.set('HAVE_DIAGNOSTIC_DEPRECATED_DECLARATIONS', true)
+  conf_data.set('HAVE_DIAGNOSTIC_DEPRECATED_DECLARATIONS', 1)
 endif
 
 c_args = [
@@ -101,24 +101,24 @@
 python2_installation = pymod.find_installation('python2', required: get_option('python2'))
 
 if get_option('libcurl').enabled() and curl_found.found()
-  conf_data.set('HAVE_LIBCURL', true)
+  conf_data.set('HAVE_LIBCURL', 1)
   libsixel_deps += [curl_found]
 endif
 
-if get_option('jpeg').enabled() and jpeg_found
-  conf_data.set('HAVE_JPEG', true)
+if get_option('jpeg').enabled() and jpeg_found.found()
+  conf_data.set('HAVE_JPEG', 1)
   libsixel_deps += [jpeg_found]
 endif
 
-if get_option('png').enabled() and png_found
-  conf_data.set('HAVE_PNG', true)
+if get_option('png').enabled() and png_found.found()
+  conf_data.set('HAVE_PNG', 1)
   libsixel_deps += [png_found]
 endif
 
 loaders = ['stb-image']
 
 if get_option('gd').enabled() and gd_found.found()
-  conf_data.set('HAVE_GD', true)
+  conf_data.set('HAVE_GD', 1)
   libsixel_deps += [gd_found]
   loaders += ['gd']
 
@@ -132,19 +132,19 @@
 
   foreach f : gd_funcs
     if cc.has_function(f, dependencies: gd_found)
-      conf_data.set('HAVE_DECL_@0@'.format(f.to_upper()), true)
+      conf_data.set('HAVE_DECL_@0@'.format(f.to_upper()), 1)
     endif
   endforeach
 endif
 
 if get_option('gdk-pixbuf2').enabled() and gdkpixbuf2_found.found()
-  conf_data.set('HAVE_GDK_PIXBUF2', true)
+  conf_data.set('HAVE_GDK_PIXBUF2', 1)
   libsixel_deps += [gdkpixbuf2_found]
   loaders += ['gdk-pixbuf2']
 endif
 
 if have_getopt_long
-  conf_data.set('HAVE_GETOPT_LONG', true)
+  conf_data.set('HAVE_GETOPT_LONG', 1)
 endif
 
 configure_file(output: 'config.h', configuration: conf_data)