diff --git a/definitions/grib1/section.1.def b/definitions/grib1/section.1.def
index 3bc733b1f..beef92bbb 100644
--- a/definitions/grib1/section.1.def
+++ b/definitions/grib1/section.1.def
@@ -336,9 +336,9 @@ meta md5Product md5(offsetSection1,section1Length,gridDefinition,section1Flags,d
 concept_nofail paramIdForConversion(zero, "paramIdForConversion.def", conceptsDir2, conceptsDir1) : long_type,read_only;
 
 # ECC-1954
-if (productDefinitionTemplateNumber == 0 && defined(perturbationNumber) && numberOfForecastsInEnsemble > 0) {
+if (productDefinitionTemplateNumber == 0 && defined(perturbationNumber) && defined(numberOfForecastsInEnsemble) && numberOfForecastsInEnsemble > 0) {
   alias productDefinitionTemplateNumber = one; # ensemble instant
 }
-if (productDefinitionTemplateNumber == 8 && defined(perturbationNumber) && numberOfForecastsInEnsemble > 0) {
+if (productDefinitionTemplateNumber == 8 && defined(perturbationNumber) && defined(numberOfForecastsInEnsemble) && numberOfForecastsInEnsemble > 0) {
   alias productDefinitionTemplateNumber = eleven; # ensemble interval
 }