diff --git a/changelog.json b/changelog.json
index 1e69475..f868d8c 100644
--- a/changelog.json
+++ b/changelog.json
@@ -4,11 +4,13 @@
     "date": "",
     "en": [
       "Opening the Awards panel no longer pulls the whole logbook several times at once — a large log briefly took gigabytes of memory.",
-      "Awards: the Missing refs button now only appears where it means something — a worldwide award like POTA could only ever answer “nothing found”."
+      "Awards: the Missing refs button now only appears where it means something — a worldwide award like POTA could only ever answer “nothing found”.",
+      "Worked before: a prefixed call like ZA/OE8NDR matched every other visitor to that country instead of that one operator."
     ],
     "fr": [
       "Ouvrir le panneau Awards ne tire plus plusieurs fois le journal entier en même temps — un gros log occupait brièvement des gigaoctets de mémoire.",
-      "Awards : le bouton Réf. manquantes n’apparaît plus que là où il a un sens — un diplôme mondial comme POTA ne pouvait répondre que « aucun manque »."
+      "Awards : le bouton Réf. manquantes n’apparaît plus que là où il a un sens — un diplôme mondial comme POTA ne pouvait répondre que « aucun manque ».",
+      "Déjà contacté : un indicatif préfixé comme ZA/OE8NDR rapprochait tous les autres visiteurs du pays au lieu de ce seul opérateur."
     ]
   },
   {
diff --git a/internal/qso/callmatch_test.go b/internal/qso/callmatch_test.go
index 642bb88..d94d893 100644
--- a/internal/qso/callmatch_test.go
+++ b/internal/qso/callmatch_test.go
@@ -2,6 +2,32 @@ package qso
 
 import "testing"
 
+// baseCall picks the operator's OWN callsign out of a portable form. The slash
+// carries a qualifier on either side and which side depends on what it is, so
+// this is the whole difficulty.
+func TestBaseCall(t *testing.T) {
+	for in, want := range map[string]string{
+		"RK3DWA":      "RK3DWA",
+		"RK3DWA/3":    "RK3DWA", // call-area digit
+		"RK3DWA/P":    "RK3DWA", // portable
+		"RK3DWA/QRP":  "RK3DWA",
+		"RK3DWA/MM":   "RK3DWA",
+		"ZA/OE8NDR":   "OE8NDR", // an Austrian in Albania — the case that prompted this
+		"ZA/IZ2DPX":   "IZ2DPX",
+		"F/DL1ABC":    "DL1ABC",
+		"F/DL1ABC/P":  "DL1ABC",
+		"KH6/K6ABC":   "K6ABC",
+		"VP2E/W1ABC":  "W1ABC",
+		"3DA0/ZS1ABC": "ZS1ABC",
+		"9A/S51AB":    "S51AB",
+		"/RK3DWA":     "RK3DWA",
+	} {
+		if got := baseCall(in); got != want {
+			t.Errorf("baseCall(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
+
 // The predicate behind "Worked before". Exact when folding is off; with it on,
 // a station's portable forms are one operator — and the fold has to work from
 // either end, because you may type the base call or the portable one.
@@ -10,25 +36,61 @@ func TestCallMatch(t *testing.T) {
 		t.Errorf("exact: got %q %v", pred, args)
 	}
 
-	// Typing the base call: match it and everything suffixed off it.
-	pred, args := callMatch("RK3DWA", true)
-	if pred != "(callsign = ? OR callsign LIKE ?)" {
-		t.Errorf("variants predicate = %q", pred)
-	}
-	if len(args) != 2 || args[0] != "RK3DWA" || args[1] != "RK3DWA/%" {
-		t.Errorf("variants args = %v, want [RK3DWA RK3DWA/%%]", args)
-	}
+	// Typing the base call: match it, everything suffixed off it, and every
+	// prefixed form of it.
+	_, args := callMatch("RK3DWA", true)
+	want := []any{"RK3DWA", "RK3DWA/%", "%/RK3DWA", "%/RK3DWA/%"}
+	assertArgs(t, "base call", args, want)
 
-	// Typing a portable form must reach the plain call too — the suffix is
+	// Typing a portable form must reach the plain call too — the qualifier is
 	// stripped from the INPUT, not just matched in the column.
 	_, args = callMatch("RK3DWA/3", true)
-	if len(args) != 2 || args[0] != "RK3DWA" || args[1] != "RK3DWA/%" {
-		t.Errorf("portable input args = %v, want [RK3DWA RK3DWA/%%]", args)
+	assertArgs(t, "portable input", args, want)
+}
+
+// A prefixed call is the same operator, and NOT every other visitor to that
+// country.
+//
+// Matching on the part before the slash made ZA/OE8NDR the station "ZA", so the
+// worked-before list for one Austrian operating from Albania showed every other
+// ZA/ guest — two Italians — and counted them as four contacts "with this
+// call". Reported from a screenshot of exactly that.
+func TestCallMatchPrefixedIsTheOperatorNotTheCountry(t *testing.T) {
+	_, args := callMatch("ZA/OE8NDR", true)
+	assertArgs(t, "ZA/OE8NDR", args, []any{"OE8NDR", "OE8NDR/%", "%/OE8NDR", "%/OE8NDR/%"})
+
+	for _, a := range args {
+		if s, _ := a.(string); s == "ZA" || s == "ZA/%" {
+			t.Fatalf("the country prefix is still being matched as a station: %v", args)
+		}
 	}
 
-	// A leading slash is not a suffix marker — dropping to "" there would match
-	// the entire logbook.
-	if _, args := callMatch("/RK3DWA", true); args[0] != "/RK3DWA" {
-		t.Errorf("leading slash: args[0] = %v, want the call unchanged", args[0])
+	// And the two are not each other: nothing in one operator's predicate can
+	// select the other's call.
+	_, other := callMatch("ZA/IZ2DPX", true)
+	assertArgs(t, "ZA/IZ2DPX", other, []any{"IZ2DPX", "IZ2DPX/%", "%/IZ2DPX", "%/IZ2DPX/%"})
+}
+
+// A base too short to be a callsign falls back to an exact match. "F/DL1ABC"
+// resolves fine, but a malformed entry must never produce a LIKE that selects
+// half the logbook.
+func TestCallMatchRefusesAShortBase(t *testing.T) {
+	for _, call := range []string{"F/", "9A", "/P", "K/M"} {
+		pred, args := callMatch(call, true)
+		if pred != "callsign = ?" || len(args) != 1 {
+			t.Errorf("%q produced %q %v — want an exact match", call, pred, args)
+		}
+	}
+}
+
+func assertArgs(t *testing.T, what string, got, want []any) {
+	t.Helper()
+	if len(got) != len(want) {
+		t.Fatalf("%s: args %v, want %v", what, got, want)
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Fatalf("%s: args %v, want %v", what, got, want)
+		}
 	}
 }
diff --git a/internal/qso/qso.go b/internal/qso/qso.go
index 78eba1e..3e51c88 100644
--- a/internal/qso/qso.go
+++ b/internal/qso/qso.go
@@ -1723,26 +1723,77 @@ type BandMode struct {
 // rendering a recent-contacts mini-list.
 const maxWorkedEntries = 50
 
+// operatorSuffixes are the appendages that qualify a callsign without changing
+// whose it is. A bare digit (RK3DWA/3) counts too, handled separately.
+var operatorSuffixes = map[string]bool{
+	"P": true, "M": true, "MM": true, "AM": true, "QRP": true,
+	"A": true, "B": true, "J": true, "LH": true, "R": true, "T": true,
+}
+
+// baseCall extracts the operator's OWN callsign from a portable form.
+//
+// The slash carries the qualifier on either side, and which side depends on
+// what it is: RK3DWA/3 and RK3DWA/P append to the call, while ZA/OE8NDR and
+// F/DL1ABC put a country prefix in front of it. Taking the part before the
+// slash — which is what this used to do — reads ZA/OE8NDR as the station "ZA".
+//
+// So: drop the known qualifiers, and of what is left take the longest part. A
+// prefix is short by nature (ZA, F, KH6, VP2E) and a callsign is not.
+func baseCall(call string) string {
+	if !strings.Contains(call, "/") {
+		return call
+	}
+	best := ""
+	for _, p := range strings.Split(call, "/") {
+		if p == "" || operatorSuffixes[p] {
+			continue
+		}
+		if len(p) == 1 && p[0] >= '0' && p[0] <= '9' {
+			continue // the call-area digit
+		}
+		if len(p) > len(best) {
+			best = p
+		}
+	}
+	if best == "" {
+		return call
+	}
+	return best
+}
+
 // callMatch builds the WHERE fragment that selects one station's QSOs.
 //
 // Exact by default. With variants on, an operator's portable forms count as the
 // same station: RK3DWA, RK3DWA/3, RK3DWA/P and RK3DWA/QRP are one person, and
 // someone asking "have I worked RK3DWA?" means the person, not the string.
 // Typing 21 QSOs' worth of history only when you happen to add "/3" is the
-// behaviour this replaces. The suffix is stripped from what was TYPED too, so
-// it matches both ways round — RK3DWA/3 also finds the plain RK3DWA contacts.
+// behaviour this replaces.
+//
+// PREFIXED FORMS MATCH TOO, and getting that wrong is what prompted this.
+// Matching on the part before the slash turned ZA/OE8NDR into the station "ZA",
+// so the worked-before list for one Austrian operating from Albania showed
+// every OTHER visitor to Albania — two Italians and himself — and counted them
+// as four contacts "with this call".
 //
 // Deliberately NOT a bare "starts with": LIKE 'RK3DWA%' would also drag in
 // RK3DWAB, which is a different station. The '/' is what makes it the same one.
+// And the variant match is only used on a base of three characters or more —
+// below that a prefix could match half the log.
 func callMatch(call string, variants bool) (string, []any) {
 	if !variants {
 		return "callsign = ?", []any{call}
 	}
-	base := call
-	if i := strings.IndexByte(base, '/'); i > 0 {
-		base = base[:i]
+	base := baseCall(call)
+	if len(base) < 3 {
+		return "callsign = ?", []any{call}
 	}
-	return "(callsign = ? OR callsign LIKE ?)", []any{base, base + "/%"}
+	return "(callsign = ? OR callsign LIKE ? OR callsign LIKE ? OR callsign LIKE ?)",
+		[]any{
+			base,               // OE8NDR
+			base + "/%",        // OE8NDR/P
+			"%/" + base,        // ZA/OE8NDR
+			"%/" + base + "/%", // ZA/OE8NDR/P
+		}
 }
 
 // WorkedBefore returns aggregated history at both callsign and DXCC level.
diff --git a/internal/qso/stats_test.go b/internal/qso/stats_test.go
index 31205b0..29399ec 100644
--- a/internal/qso/stats_test.go
+++ b/internal/qso/stats_test.go
@@ -70,12 +70,12 @@ func TestStatsNoNilSlices(t *testing.T) {
 }
 
 // Contest metrics over a window. The two traps:
-//   1. "Best hour" must be the best ROLLING 60 minutes, not the best clock hour —
-//      a run straddling 13:45–14:45 is invisible to clock-hour bucketing, and the
-//      rolling figure is the one contesters quote.
-//   2. Both rates must be reported: QSOs ÷ whole window (honest, breaks included)
-//      AND QSOs ÷ hours actually operated. Quoting only the latter is how an
-//      8-hour effort gets sold as a 48-hour score.
+//  1. "Best hour" must be the best ROLLING 60 minutes, not the best clock hour —
+//     a run straddling 13:45–14:45 is invisible to clock-hour bucketing, and the
+//     rolling figure is the one contesters quote.
+//  2. Both rates must be reported: QSOs ÷ whole window (honest, breaks included)
+//     AND QSOs ÷ hours actually operated. Quoting only the latter is how an
+//     8-hour effort gets sold as a 48-hour score.
 func TestContestPeriodMetrics(t *testing.T) {
 	base := time.Date(2026, 5, 30, 12, 0, 0, 0, time.UTC)
 	at := func(min int) time.Time { return base.Add(time.Duration(min) * time.Minute) }
@@ -90,8 +90,8 @@ func TestContestPeriodMetrics(t *testing.T) {
 		times = append(times, entry{t: at(240 + i*5), op: "F5XYZ"}) // 16:00 …
 	}
 
-	from := base                       // 12:00
-	to := base.Add(6 * time.Hour)      // 18:00 → a 6-hour window
+	from := base                  // 12:00
+	to := base.Add(6 * time.Hour) // 18:00 → a 6-hour window
 	var s Stats
 	s.periodMetrics(times, from, to, time.Time{}, time.Time{})