diff --git a/lang/funcs/core/fmt/printf_func.go b/lang/funcs/core/fmt/printf_func.go
index 23e468cf..71155778 100644
--- a/lang/funcs/core/fmt/printf_func.go
+++ b/lang/funcs/core/fmt/printf_func.go
@@ -85,6 +85,13 @@ func (obj *PrintfFunc) Polymorphisms(partialType *types.Type, partialValues []ty
 		}
 	}
 
+	// FIXME: we'd like to pre-compute the interpolation if we can, so that
+	// we can run this code properly... for now, we can't, so it's a compile
+	// time error...
+	if partialValues[0] == nil {
+		return nil, fmt.Errorf("could not determine type from format string")
+	}
+
 	format := partialValues[0].Str() // must not panic
 	typList, err := parseFormatToTypeList(format)
 	if err != nil {
diff --git a/lang/interpret_test/TestAstFunc2/printfinterpolate0.output b/lang/interpret_test/TestAstFunc2/printfinterpolate0.output
new file mode 100644
index 00000000..9e048e47
--- /dev/null
+++ b/lang/interpret_test/TestAstFunc2/printfinterpolate0.output
@@ -0,0 +1 @@
+# err: err3: polymorphic signatures for func `fmt.printf` could not be found: could not determine type from format string
diff --git a/lang/interpret_test/TestAstFunc2/printfinterpolate0/main.mcl b/lang/interpret_test/TestAstFunc2/printfinterpolate0/main.mcl
new file mode 100644
index 00000000..4a227571
--- /dev/null
+++ b/lang/interpret_test/TestAstFunc2/printfinterpolate0/main.mcl
@@ -0,0 +1,10 @@
+import "fmt"
+
+$str1 = "big"
+$str2 = "world"
+
+# FIXME: we'd like to pre-compute the interpolation if we can, so that we can
+# run this code properly... for now, we can't, so it's a compile time error...
+print "print1" {
+	msg => fmt.printf("hello ${str1} %s", $str2),
+}