diff --git a/process_files.go b/process_files.go
index b95b9cb0..de9fbc85 100644
--- a/process_files.go
+++ b/process_files.go
@@ -76,7 +76,12 @@ func (v *Venom) readFiles(ctx context.Context, filesPath []string) (err error) {
 		// we take default vars from the testsuite, only if it's not already is global vars
 		for k, value := range varsFromPartial {
 			if _, ok := varCloned[k]; !ok || (varCloned[k] == "{}" && varCloned["__Len__"] == "0") {
-				varCloned[k] = value
+				// we interpolate the value of vars here, to do it only once per ts
+				valueInterpolated, err := interpolate.Do(value, varsFromPartial)
+				if err != nil {
+					return errors.Wrapf(err, "unable to parse variable %q", k)
+				}
+				varCloned[k] = valueInterpolated
 			}
 		}
 
diff --git a/tests/random_vars.yml b/tests/random_vars.yml
new file mode 100644
index 00000000..97e68da2
--- /dev/null
+++ b/tests/random_vars.yml
@@ -0,0 +1,20 @@
+name: testsuite
+vars:
+  phone_number: "+3375{{ randNumeric 7 }}"
+testcases:
+- name: test 1
+  steps:
+  - type: exec
+    script: echo '{{.phone_number}}'
+    info: '{{.phone_number}} test 1'
+    vars:
+      myvariable:
+        from: result.systemout
+        regex: ([a-z0-9\+]+)
+- name: test 2
+  steps:
+  - type: exec
+    script: echo '{{.phone_number}}'
+    info: '{{.phone_number}} test 2'
+    assertions:
+    - result.systemout ShouldEqual {{.test-1.myvariable}}